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draft-hou-sigtran-tua-00

Description: Request For Comments

You can download source copies of the file as follows:

draft-hou-sigtran-tua-00.txt in text format.

Listed below is the contents of file draft-hou-sigtran-tua-00.txt.


TERNET-DRAFT                                                Jianxing Hou
Internet Engineering Task Force                                Ming Lin
                                                    Huawei Technologies
                                                             
Issued:  1 April 2001                                            
Expires: 1 October 2001                                         
                                                        

                SS7 TCAP-User Adaptation Layer (TUA) 
                   <draft-hou-sigtran-tua-00.txt>

Status of This Memo 
   This document is in full conformance with all provisions of Section
   10 of RFC 2026.Internet-Drafts are working ocuments of the Internet
   Engineering Task Force (IETF), its areas,and its working groups. 
   Note that other groups may also distribute working documents as 
   Internet-Drafts.

Internet-Drafts are draft documents valid for a maximum of six months 
and may be updated, replaced, or obsoleted by other documents at any 
time.It is inappropriate to use Internet-Drafts as reference material 
or to cite them other than as 'work in progress.'

     The list of current Internet-Drafts can be accessed at
     http://www.ietf.org/ietf/1id-abstracts.txt

     The list of Internet-Draft Shadow Directories can be accessed at
     http://www.ietf.org/shadow.html.

To learn the current status of any Internet-Draft, please check the 
'1id-abstracts.txt' listing contained in the Internet- Drafts Shadow 
Directories on ftp.is.co.za (Africa), nic.nordu.net (Europe), 
munnari.oz.au (Pacific Rim), ftp.ietf.org (US East Coast), or 
ftp.isi.edu (US West Coast).

Abstract
     This document defines a protocol for the transport of any SS7
     TCAP-User signaling (e.g.,INAP,MAP , etc.) over IP using the 
     Stream Control Transport Protocol.  The protocol  should be 
     modular and symmetric, to allow it to work in diverse 
     architectures, such as a Signaling Gateway to IP Signaling 
     Endpoint architecture .  Protocol elements are added to allow 
     seamless operation between  peers in the SS7 and IP domains.

Internet Drift       SS7 TCAP-User Adaptation Layer       April1,2001

Abstract.............................................................1
1. Introduction......................................................2
 1.1 Scope...........................................................3
 1.2 Terminology.....................................................3
 1.3 Signaling Transport Architecture................................5
 1.4 Services Provided by the TUA Layer.............................10
 1.5 Internal Functions Provided in the TUA Layer...................10
 1.6 Definition of TUA Boundaries...................................12
2. Conventions......................................................14
3. Protocol Elements................................................14
 3.1 Common Message Header..........................................15
 3.2  TUA Message Header............................................18
 3.3  Dialogue Handling(DH)Message..................................18
 3.4 Component Handling(CH) Message.................................26
 3.5 SS7 Signaling Network Management Messages......................31
 3.6 Application Server Process Maintenance Messages................34
 3.7 ASP Traffic Maintenance Messages...............................36
 3.8 Management Messages............................................39
 3.9 SGP Traffic Maintenance (SGPTM) Messages.......................40
 3.10 Common Parameters.............................................40
 3.11 TUA-Specific parameters.......................................50
4. Procedures.......................................................62
 4.1 TCAP _ TUA Interworking at the SG..............................62
 4.2 Primitives received from the local TUA-User....................63
 4.3 Layer Management Procedures....................................63
 4.4 TUA Management Procedures......................................64
5. Examples of TUA Procedures.......................................74
 5.1 Establishment of Association and Traffic between SGPs and ASPs.74
 5.2 IP-IP Architecture.............................................79
6. Security.........................................................81
 6.1 Introduction...................................................81
 6.2 Threats........................................................81
 6.3 Protecting Confidentiality.....................................82
7. IANA Considerations..............................................82
 7.1 SCTP Payload Protocol ID.......................................82
 7.2 Protocol Extensions............................................82
8. Timer Values.....................................................83
9. Acknowledgements.................................................83
10. Authors' Addresses..............................................83
11. References......................................................84

Jianxing  Hou, et al                                        [Page 2]
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1. Introduction

1.1 Scope

   There is on-going integration of SCN networks and IP networks.
Network service providers are designing all IP architectures which
include support for SS7 and SS7-like signaling protocols. IP provides
an effective way to transport user data and for operators to expand
their networks and build new services. In these networks,   there may
be some need for interworking between the SS7 and IP domains.

 This document details the delivery of TCAP-user messages and new third 
generation network protocol messages over IP between two signaling 
endpoints.Consideration is given for the transport from an SS7 
Signaling Gateway (SG) to an IP signaling node (such as an IP-resident
Database) as described in the  Framework Architecture for Signaling 
Transport [2719]. 

   The delivery mechanism SHOULD meet the following criteria:

   *  Support for transfer of SS7 TCAP-User Part messages (e.g.,INAP,
      MAP, etc.)
   *  Support for the seamless operation of TCAP-User protocol peers
   *  Support for the management of SCTP transport associations between
      a SG and one or more IP-based signaling nodes.
   *  Support for distributed IP-based signaling nodes.
   *  Support for the asynchronous reporting of status changes to 
      management

 The protocol is modular in design,allowing different implementations
 to be made, based upon the environment that needs to be supported.

1.2 Terminology

Signaling Gateway (SG) - Network element that terminates SCN signaling
and transports TCAP-User signaling over IP to an IP signaling endpoint.  

Signalling Gateway Process (SGP) - A process instance of a Signalling 
Gateway.  It serves as an active, standby or load-sharing process of a 
Signalling Gateway.

Application Server (AS) - A logical entity serving a specific Routing 
Key.An example of an Application Server is a virtual IP database 
element handling all request for a TCAP-user.  The AS contains a set
of one or more unique Application Server Processes,of which one or more
is normally actively processing traffic.

Jianxing  Hou, et al                                        [Page 3]
Internet Drift       SS7 TCAP-User Adaptation Layer       April1,2001

Application Server Process (ASP) - An Application Server Process serves
as an active or standby process of an  Application Server(e.g., part of
a distributed signaling node or database element). Examples of ASPs are
MGCs,IP SCPs, or IP-based HLRs.  An ASP contains an SCTP end-point and
may be configured to process traffic within more than one Application 
Server.

Association - An association refers to an SCTP association. The
association provides the transport for the delivery of TCAP-User
protocol data units and TUA adaptation layer peer messages.

Routing Key - The Routing Key describes a set of SS7 parameter and/or 
parameter-ranges that uniquely defines the range of signaling traffic 
configured to be handled by a particular Application Server.An example
would be where a Routing Key consists of a TCAP DID and SCCP SSN for 
which all traffic would be directed to a particular Application Server.
Routing Keys are mutually exclusive in the sense that a received SS7 
signaling message cannot be directed to more than one Routing Key. In
the case of TUA, the  Routing Key should be limited to TCAP SSN or a
combination of TCAP DID and SCCP SSN to identify an AS,in order to more
easily support TCAP management procedures.

Routing Context - An Application Server Process may be configured to 
process traffic within  more than one Application Server.In this case,
the Routing Context parameter is exchanged between two ASPs,identifying
the relevant Application Server.  From the perspective of an ASP, the
Routing Context uniquely identifies the range of traffic associated 
with a particular Application Server, which the ASP is configured to
receive.There is a 1:1 relationship between a Routing Context value and
a Routing Key within an AS. Therefore the Routing Context can be viewed
as an index into an AS Table containing the AS Routing Keys.

Fail-over - The capability to re-route signaling traffic as required to
an alternate Application  Server Process, or group of ASPs, within an
Application Server in the event of failure or unavailability of a 
currently used Application Server Process. Fail-back may apply upon the
return to service of a previously unavailable  Application Server
Process.

Network Appearance - The Network Appearance identifies protocol's type
(ITU or ANSI ect)an SS7 network context (network ID) for the purposes
of logically separating the signaling traffic between the SG and the 
Application Server Processes over a common SCTP Association.  This 
partitioning is necessary where an SG is logically partitioned to 
appear as an   end-node elements in multiple separate national SS7
networks, in which case there is a separate network appearance for each

Jianxing  Hou, et al                                        [Page 4]
Internet Drift       SS7 TCAP-User Adaptation Layer       April1,2001

SS7 network. It is also necessary when an SG is configured  as an STP
and hosts multiple point codes within the same network,in which case 
each point code is a separate network appearance.

Network Byte Order - Most significant byte first, a.k.a. Big Endian.

Layer Management - Layer Management is a nodal function in an SG or ASP
that handles the inputs and outputs between the TUA layer and a local
management entity.

Host - The computing platform that the ASP process is running on.

Stream - A stream refers to an SCTP stream; a uni-directional logical
channel established from one SCTP endpoint to another associated SCTP
endpoint,within which all user messages are delivered in-sequence 
except for those submitted to the un-ordered delivery service.

Transport address - an address which serves as a source or destination
for the unreliable packet transport service used by SCTP. In IP 
networks, a transport address is defined by the combination  of an IP
address and an SCTP port number.  Note, only   one SCTP port may be 
defined for each endpoint, but each SCTP endpoint may have multiple IP
addresses.

1.3 Signaling Transport Architecture

The framework architecture that has been defined for SCN signaling
transport over IP [2719] uses  multiple components, including an IP
transport protocol,a signaling common transport protocol and an
adaptation module to support the services expected by a particular SCN
signaling protocol from its underlying protocol layer.

  1.3.1 Protocol Architecture
   In this architecture, the TCAP and TUA layers interface in the SG.
   There needs to be interworking between the TCAP and TUA layers to
   provide for the seamless transfer of the user messages as well as
   the management messages.  

        ********   SS7   ***************   IP   ********
        * SEP  *---------*             *--------*      *
        *  or  *         *      SG     *        * ASP  *
        * STP  *         *             *        *      *
        ********         ***************        ********
                      
        +------+                                +------+
        | TC_U |                                | TC_U |
 
Jianxing  Hou, et al                                        [Page 5]
Internet Drift       SS7 TCAP-User Adaptation Layer       April1,2001 
 
 
        +------+         +------+------+        +------+ 
        | TCAP |         | TCAP | TUA  |        | TUA  |
        +------+         +------+------+        +------+
        | SCCP |         | SCCP |      |        |      |
        +------+         +------+      |        |      |
        | MTP3 |         | MTP3 | SCTP |        |      |
        +------|         +------+      |        | SCTP |
        | MTP2 |         | MTP2 |      |        |      |
        +------+         +------+------+        +------+
        |  L1  |         |  L1  |  IP  |        |  IP  |
        +------+         +------+------+        +------+
            |               |         |            |
            +---------------+         +------------+

          TC_U - TCAP  USER  (e.g. - MAP/INAP)
          STP  - SS7 Signaling Transfer Point

     In this case, the TCAP messages are routed on SSN or SSN+DID. The
     TCAP-User identified by SSN or SSN+DID is regarded as local to the
     SG. This means from SS7 point of view, the TCAP-user is located at
     the SG.

   By means of configuration, the SG knows the local TCAP-user is
   actually representing an AS, serviced by a set of ASPs working in
   n+k redundancy mode.  An ASP is selected and a TCAP message is sent
   on the appropriate SCTP association/stream.

   Actually, the primitive interface between TCAP and TCAP-user is
   transported here over TUA.  An example for a INAP/MAP  message
   exchange between SEP and ASP is given below.

   Address information in  message from SG to ASP :
     -  Network appearance : based on SS7 network ID and Protocol Type,
     -  Source address : valid combination of SSN, PC and GT, as
        needed for back-routing,
     -  Destination address : at least SSN , to select the 
       TCAP-user at the ASP.

   The Network Appearance is needed if the SG operates in more than one
   SS7 network or protocol type(ITU or ANSI,etc), since PC and SSN only 
   have meaning within a specific SS7 network. If SG receives a message
   from SS7 network,it will determine which AS the message is sent to
  (based on SSN or SSN+DID within the message),then it will select an 
   active ASP based on implementation,and select a Stream ID for the
   message,and then the message can be sent to proper ASP. 
     
  Address information in  message from ASP to SG :

Jianxing  Hou, et al                                        [Page 6]
Internet Drift       SS7 TCAP-User Adaptation Layer       April1,2001

     - Network appearance : as received in previous message,
     - Source address : unique ASP address that when used as
       SCCP called party address in the SEP, MUST yield the
       same ASP again; the SSN could be sufficient,  
     - Destination address : copied from source address in received
       and response message.
   When ASP receives a message from TCAP-User,it will select a SGP
   through TCAP DID based on implementation,then select a Stream ID to
   the message,and then the message can be sended to SG.

1.3.2 All IP Architecture

   This architecture can be used to carry a protocol which uses the
   transport services of TCAP, but is contained with an IP network.
   This allows extra flexibility in developing networks, especially
   when interaction between legacy signaling is not needed.  The
   architecture removes the need for signaling gateway functionality.

          ********   IP   ********
          *      *--------*      *
          *  AS  *        *  AS  *
          *      *        *      *
          ********        ********

          +------+        +------+
          |  AP  |        |  AP  |
          +------+        +------+
          | TUA  |        | TUA  |
          +------+        +------+
          | SCTP |        | SCTP |
          +------+        +------+
          |  IP  |        |  IP  |
          +------+        +------+
             |                |
             +----------------+

       AP - Application Protocol (e.g. - MAP/INAP)

   The SCTP protocol takes care about the case where a collision occurs
   during initiation.

1.3.3 Generalized Point-to-Point Network Architecture

   Figure 1 shows an example network architecture which can support
   robust operation and failover support.  There needs to be some
   management resources at the AS to manage traffic.

Jianxing  Hou, et al                                        [Page 7]
Internet Drift       SS7 TCAP-User Adaptation Layer       April1,2001

         ***********
         *   AS1   *
         * +-----+ * SCTP Associations
         * |ASP1 +-------------------+
         * +-----+ *                 |                   ***********
         *         *                 |                   *   AS3   *
         * +-----+ *                 |                   * +-----+ *
         * |ASP2 +-----------------------------------------+ASP1 | *
         * +-----+ *                 |                   * +-----+ *
         *         *                 |                   *         *
         * +-----+ *                 |                   * +-----+ *
         * |ASP3 | *            +--------------------------+ASP2 | *
         * +-----+ *            |    |                   * +-----+ *
         ***********            |    |                   ***********
                                |    |
         ***********            |    |                   ***********
         *   AS2   *            |    |                   *   AS4   *
         * +-----+ *            |    |                   * +-----+ *
         * |ASP1 +--------------+    +---------------------+ASP1 | *
         * +-----+ *                                     * +-----+ *
         *         *                                     *         *
         * +-----+ *                                     * +-----+ *
         * |ASP2 +-----------------------------------------+ASP1 | *
         * +-----+ *                                     * +-----+ *
         *         *                                     ***********
         * +-----+ *
         * |ASP3 | *
         * +-----+ *
         *         *
         ***********

                    Figure 1: Generalized Architecture

   In this example, the Application Servers are shown residing within
   one logical box, with ASPs located inside.  In fact, an AS could be
   distributed among several hosts.  In such a scenario, the host
   should share state as protection in the case of a failure.

   Additionally, in a distributed system, one ASP could be registered
   to more than one AS.  This draft should not restrict such systems -
   though such a case in not specified.

1.3.4 Generalized Signaling Gateway Network Architecture
      When interworking between SS7 and IP domains is needed, the SG 
  acts as the gateway node between the SS7 network and the IP network.
 
Jianxing  Hou, et al                                        [Page 8]
Internet Drift       SS7 TCAP-User Adaptation Layer       April1,2001

  The SG will transport TCAP-user signaling traffic from the SS7 
  network to the IP-based signaling nodes(for example IP-resident
  Databases). The Signaling Gateway can be considered as a group of 
  Application Servers with additional functionality to interface 
  towards an SS7 network.

     The TUA protocol should be flexible enough to allow different 
 configurations and transport technology to allow the network operators
 to meet their operation, management and performance requirements.
 
   Figure 2 shows a possible realization of this architecture, with
   Signaling Gateway functionality.

  Signaling Gateway

 ************
 *   SG     *                                            AS1
 * ******** *                                        **************
 * *      *_*________________________________________*  ********  *
 * *      * *                               _________*  * ASP1 *  *
 * * SGP1 * *  SCTP Associations           |         *  ********  *
 * *      *_*______________________        |         *            *
 * ******** *                      |       |         *  ********  *
 *          *                      |       |         *  * ASP2 *  *
 *          *                      |       |         *  ********  *
 *          *                      |       |         *     .      *
 *          *                      |       |         *     .      *
 *          *                      |       |         *     .      *
 * ******** *                      |       |         * ************
 * *      *_*______________________|_______|
 * *      * *                      |
 * * SGP2 * *   SCTP Associations  |
 * *      *_*___________           |
 * *      * *           |          |                    AS2
 * ******** *           |          |                 **************
 *          *           |          |_________________*  ********  *
 *          *           |____________________________*  * ASP1 *  *
 *          *                                        *  ********  *
 *          *                                        *            *
 ************                                        *  ********  *
                                                     *  * ASP2 *  *
                                                     *  ********  *
                                                     *     .      *
                                                     *     .      *
                                                     *     .      *
                                                     **************    
              Figure 2: Signaling Gateway Architecture

Jianxing  Hou, et al                                        [Page 9]
Internet Drift       SS7 TCAP-User Adaptation Layer       April1,2001

1.3.5 ASP Fail-over Model and Terminology

  The TUA protocol supports ASP fail-over functions in order to support
a high availability of transaction processing capability.An Application
Server can be considered as a list of all ASPs configured/registered to
handle TCAP-user messages within a certain range of routing information,
known as a Routing Key.  One or more ASPs in the list may normally be 
active to handle traffic, while others may be inactive but available in
the event of failure or unavailability of the active ASP(s).

1.4 Services Provided by the TUA Layer

1.4.1 Support for the transport of TCAP-User Messages

   The TUA needs to support the transfer of TCAP-user messages.The TUA 
   layer at the SG needs to seamlessly transport the user messages.

1.4.2 Native Management Functions

   The TUA layer may provide management of the underlying SCTP layer to
ensure that transport is available according to the degree specified by
the TCAP-user application.

  The TUA layer provides the capability to indicate errors associated 
  with the TUA-protocol messages and to provide notification to local
  management and the remote peer as is necessary.

1.4.3 Support for passing the SCCP management message

   The TUA layer should provide passing transparently availability and
non-availability of SCCP (local or remote) between the SCN network and
the IP network. (see ITU-T Q.771 chap 2.2.3) It should:

   -Provide an indication to the TCAP-user at an ASP that a remote SS7 
    endpoint/peer is unreachable.
   -Provide an indication to the TCAP-user at an ASP that a remote SS7
    endpoint/peer is reachable.
   -Provide congestion indication to TCAP-user at an ASP.

1.5 Internal Functions Provided in the TUA Layer

1.5.1 Address Translation and Mapping at the SG

   The SG MUST provide address translation and mapping functions to 
direct messages received from the SS7 network to the appropriate IP

Jianxing  Hou, et al                                        [Page 10]
Internet Drift       SS7 TCAP-User Adaptation Layer       April1,2001

destination.
   In order to support message distribution,the SG maintains an address
translation table, which maps the incoming SS7 messages to the 
appropriate AS.  The relevant fields of the incoming SS7 message is 
compared to the existing Routing Keys.  The Routing Keys reference an
Application Server,which will have one or more ASPs processing traffic
for the AS.  The availability and status of the ASPs is handled by TUA
ASP management messages.
   Possible SS7 address/routing information that comprise a Routing Key
entry includes, for example,SCCP subsystem number, or TCAP transaction 
ID. Some possibilities  include:
           SSN
           SSN+TCAP DID

   An Application Server maintains a list of ASPs that are available to
process the traffic.  The list is dynamic, based upon the availability 
of the individual ASPs in the list.TUA ASP management messages are used
to convey the status of these ASPs and their availability in failover 
situations.

   Normally, one or more ASPs is active in the ASP (i.e., currently 
processing traffic) but in certain failure and transition cases it is
possible that there may not be an active ASP available.Both 
load-sharing and backup scenarios are supported.

   If there is no Routing Key match for an incoming SS7 message, a 
default treatment MUST be specified.  Possible solutions are to provide
a default Application Server to direct all unallocated  traffic to a 
(set of) default ASP(s), or to drop the messages and provide a 
notification to management.The treatment of unallocated traffic is 
implementation dependent.

1.5.2 Address Translation and Mapping at the ASP

   In order to direct messages to the SS7 network, the ASP must choose 
the proper  SGP for a given message. This is accomplished by observing
SGP availability and is implementation dependent.
   A remote Signaling Gateway may be composed of one or more SGPs that
are capable of routing SS7 traffic.As is the case with ASPs, a dynamic
list of SGPs in an SG can be maintained, taking into account the 
availability status of the individual SGPs, configuration changes and 
fail-over mechanisms. There is, however, no TUA messaging to manage the
status of an SGP. Whenever an SCTP association to an SGP exists, it is
assumed to be available.  Also, every SGP of one SG communicating with
one ASP regarding one AS provides identical SS7 connectivity to this 
ASP.

Jianxing  Hou, et al                                        [Page 11]
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1.5.3 SCTP Stream Mapping

   The TUA supports SCTP streams. The SG/AS needs to maintain a list of
SCTP and TUA-users for mapping purposes.TCAP-users requiring sequenced 
message transfer need to be sent over a stream supporting sequenced 
delivery.
   TUA MUST use stream 0 for TUA management messages. It is recommended
that sequenced delivery be in order to preserve the order of management
message delivery.

1.5.4 TCAP DID Mapping

 Because Both TCAP and TCAP-User can assign DID independently,it is
 possible that TCAP and TCAP-User assign same value to different 
 message at the same time, but it brings some problems. To solve this
 problem, TUA need support TCAP DID mapping. The TUA needs to maintain
 a list of incoming message's DID and outgoing message's DID for 
 mapping purposes.The solution in more details will be lodged via 
 discussion.
    
1.6 Definition of TUA Boundaries

1.6.1 Definition of the upper boundary

   The following primitives are supported between the TUA and an 
TCAP-user (a reference to ITU and ANSI sections where these primitives
and corresponding parameters are described, is also given).

1.6.1.1 Primitives for  ITU
  Name         |   Type     |    Reference (ITU)       | TUA  Message 
----------------------------------------------------------------------
 TC-UNI        | Request    | ITU-Q.711 chap3.1.2.2.1  |Unidirectional 
               |Indication  |                          |               
----------------------------------------------------------------------
 TC-BEGIN      | Request    |ITU-Q.711 chap3.1.2.2.2.1 | Query         
               |Indication  |                          |            
----------------------------------------------------------------------
 TC-CONTINUE   | Request    | ITU-Q.711 chap3.1.2.2.2.2| Conversation
               | Indication | ITU-Q.711 chap3.1.2.2.2.3|            
----------------------------------------------------------------------
  TC-END       | Request    | ITU-Q.711 chap3.1.2.2.2.4| End          
               |Indication  |                          |               
----------------------------------------------------------------------
  TC-U-ABORT   | Request    | ITU-Q.711chap3.1.2.2.2.4 | U-Abort      
               |Indication  |                          |              
----------------------------------------------------------------------
  TC-P-ABORT   |Indication  | ITU-Q.711 chap3.1.4.2    | P_Abort      

Jianxing  Hou, et al                                        [Page 12]
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 ---------------------------------------------------------------------
  TC-NOTICE    | Indication | ITU-Q.711 chap3.1.2.2.3  | Notice       
----------------------------------------------------------------------
 TC_INVOKE     | Request    | ITU-Q.711 chap3.1.3.2    | Invoke     
               | Incation   |                          |      
----------------------------------------------------------------------
TC_RESULT_L    | Request    | ITU-Q.711 chap3.1.3.3    | Result 
---------------|            |                          |
TC_RESULT_NL   | Indication |                          |    
---------------------------------------------------------------------- 
TC_U-ERROR     | Request    |  ITU-Q.711 chap3.1.3.4   | U_Error     
               |Indication  |                          |              
----------------------------------------------------------------------
TC_U_REJECT    | Request    | ITU-Q.711 chap3.1.3.5    |              
               |Indication  |                          |              
----------------------------|                          |
TC_L_REJECT    | Request    |                          | Reject    
               |Indication  |                          |              
----------------------------| ITU-Q.711 chap3.1.4.1    |              
TC_R_REJECT    | Request    |                          |              
               | Indication |                          |              
----------------------------------------------------------------------
TC-U-CANCEL    | Request    |                          |              
---------------|            | ITU-Q.711 chap3.1.3.6    | Cancel       
TC-L-CANCEL    |Indication  |                          |             
----------------------------------------------------------------------
TC_TIMER_RESET | Request    | ITU-Q.711 chap3.1.3.6    | Timer_Reset  
----------------------------------------------------------------------

1.6.1.2  Messages for  ANSI

     TCAP   Message             |         TUA  Message
--------------------------------------------------------------------
Undirectional                   |        Unidirectional
-------------------------------------------------------------------
Query  with Permission          |     
--------------------------------|           Query
Query  without  Permission      |         
--------------------------------------------------------------------
Conversation  with  Permission  |         
--------------------------------|           Conversation          
Conversation without Permission |            
-------------------------------------------------------------------- 
Respone                         |           End  
--------------------------------------------------------------------
U_Abort                         |           U_Abort       
--------------------------------------------------------------------

Jianxing  Hou, et al                                        [Page 13]
Internet Drift       SS7 TCAP-User Adaptation Layer       April1,2001

P_Abort                         |           P_Abort                 
--------------------------------------------------------------------
Invoke  Last                    |                               
--------------------------------|           Invoke
Invoke  Not Last                |                               
--------------------------------------------------------------------
Return Result(Last)             |                                
--------------------------------|           Result
Return Result( Not Last)        |                              
--------------------------------------------------------------------
Return Error                    |           U_Error                 
--------------------------------------------------------------------
Reject                          |           Reject             
--------------------------------------------------------------------

1.6.2 Definition of the lower boundary

   The upper layer primitives provided by the SCTP are provided in
   [SCTP].

2 Conventions

   The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD,
SHOULD NOT, RECOMMENDED, NOT RECOMMENDED, MAY, and OPTIONAL, when 
they appear in this  document, are to be interpreted as described in
[RFC2119].

  In this document, the following conventions are used to describe how
a parameter is used in the message :
   M       parameter is mandatory in this message.
   O       parameter is optional in this message.
  (A)      parameter is applicable only in the ANSI TCAP message .
  (I)      parameter is applicable only in the ITU TCAP message.
 (Ind)     parameter is applicable only when this message's type is 
           Indication.
 (Req)     parameter is applicable only when this message's type is
           Request.

3 Protocol Elements

   The general message format includes a Common Message Header together
with a list of zero or more parameters as defined by the Message Type.
   For forward compatibility, all Message Types may have attached 
parameters even if none are specified in this version.

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3.1 Common Message Header

   The protocol messages for the TCAP-User Adaptation Protocol requires
a message structure which contains a version, message type, message 
length and message contents.This message header is common among all
 signaling protocol adaptation layers:

      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    Version    |   Reserved    | Message Class | Message Type  |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                        Message Length                         |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                           msg data                            |

   Note that the 'data' portion of TUA messages SHALL contain TCAP-User
   data, not the encapsulated TCAP message.

   Optional parameters can only occur at most once in an TUA message.

3.1.1 TUA Protocol Version

   The version field (ver) contains the version of the TUA adaptation
   layer.  The supported versions are:

         01   TUA version 1.0

3.1.2 Message Classes

     0         Management (MGMT) Message
     1         Reserved
     2         SS7 Signaling Network Management (SSNM) Messages
     3         ASP State Maintenance (ASPSM) Messages
     4         ASP Traffic Maintenance (ASPTM) Messages
     5         Dialogue Handling(DH) Message
     6         Component Handling(CH) Message
     7         SGP Traffic Maintenance (SGPTM) Messages
     8 - 127   Reserved by the IETF
     128 - 255 Reserved for IETF-Defined Message Class Extensions

3.1.3 Message Types

  TUA Management Messages
     0         Error (ERR)
     1         Notify (NTFY)
     2 - 127   Reserved by the IETF
 
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    128- 255  Reserved for IETF-Defined Message Class Extensions

  SS7 Signaling Network Management (SSNM) Messages
     0         Reserved
     1         Destination Unavailable (DUNA)
     2         Destination Available (DAVA)
     3         SS7 Network Congestion (SCON)     
     4         Destination User Part Unavailable (DUPU)  
     5 - 127   Reserved by the IETF
     128 - 255 Reserved for IETF-Defined Message Class Extensions

Application Server Process Maintenance (ASPM) Messages

     0         Reserved
     1         ASP Up (UP)
     2         ASP Down (DOWN)
     3         ASP Up Ack (UP ACK)
     4         ASP Down Ack (Down ACK)
     5 - 127   Reserved by the IETF
     128 - 255 Reserved for IETF-Defined Message Class Extensions

ASP Traffic Maintenance (ASPTM) Messages

     0         Reserved
     1         ASP Active (ACTIVE)
     2         ASP Inactive (INACTIVE)
     3         ASP Active Ack (ACTIVE ACK)
     4         ASP Inactive Ack (INACTIVE ACK)
     5 - 127   Reserved by the IETF
     128 - 255 Reserved for IETF-Defined Message Class Extensions

Dialogue Handling(DH) Message 
     0               Unidirectional(UNI)
     1               Query
     2               Conversation (CON)
     3               End
     4               U_Abort
     5               P_Abort
     6               Notice
     7 - 127         Reserved by the IETF
     128 - 255       Reserved for IETF-Defined Message Class Extensions

Component Handling(CH)Message
     0              Invoke
     1              Result
     2              U_Error
     3              Reject
 
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     4              Cancel
     5              Timer_Reset
     6 - 127        Reserved by the IETF
     128 - 255      Reserved for IETF-Defined Message Class Extensions

SGP Traffic Maintenance (SGPTM) Messages
    
     0              Reserved
     1              SGP Active(SGP Act)
     2-277          Reserved by the IETF 

3.1.4 Message Length

   The Message Length defines the length of the message in octets,
   including the header.

3.1.5 Tag-Length-Value Format

   TUA messages consist of a Common Header followed by zero or more
   parameters, as defined by the message type.  The Tag-Length-Value
   (TLV)  parameters contained in a message are defined in a Tag-
   Length-Value format as shown below.

      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |          Parameter Tag        |       Parameter Length        |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     \                                                               \
     /                       Parameter Value                         /
     \                                                               \
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

 Parameter Tag: 16 bits (unsigned integer)
      Tag field is a 16-bit identifier of the type of parameter. It 
      takes a value of 0 to 65534.

 Parameter Length: 16 bits (unsigned integer)
       The Parameter Length field contains the size of the parameter
       in bytes, including the Parameter Tag, Parameter Length, and 
       Parameter Value fields. The Parameter Length does not include
       any padding bytes.

 Parameter Value: variable-length.
    Parameter Value field contains the actual information to be
    transferred in the parameter.The total length of a parameter
    (including Tag, Parameter Length and Value fields) MUST be a
 
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   multiple of 4 bytes. If the length of the parameter is not a
    multiple of 4 bytes, the sender pads the Parameter at the end
    (i.e., after the Parameter Value field) with all zero bytes. 
    The length of the padding is NOT included in the parameter length
    field.A sender should NEVER pad with more than 3 bytes.The receiver
    MUST ignore the padding bytes.

 Implementation note: the use of TLV in principle allows the parameters
     to be placed in a random order in the message. However, some 
     guidelines should be considered for easy processing in the 
     following order :
   - parameters needed to correctly process other message parameters,
     preferably should precede these parameters (such as Network
     Appearance), mandatory parameters preferably should precede any
     optional parameters,
   - the data parameter will normally be the final one in the message.

3.2  TUA Message Header

In addition to the common message header, there will be a specific
message header for TUA Diagolue Handling messages and Component
Handling messages. The TUA message header will immediately follow the
Common header in these messages.

This message header contains the Dialogue ID(DID) and SSN.The format of
the DID parameter and SSN parameter are integer.

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Tag = 0x0502         |            Length             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                            SSN value                          |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Tag = 0x0501         |            Length             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                       Dialogue  ID                            |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+  

 
3.3  Dialogue Handling(DH)Message
     
   The following section describes the TUA dialogue handling messages
and parameter contents.  The general message format includes a Common
Message Header together with a list of zero or more parameters as 
defined by the Message Type.All Message Types can have attached 
parameters.

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3.3.1  Unidirectional(UNI)
 A UNI request message is for transmission of one,or several components 
invoking class 4 operations or reporting protocol errors in these 
invocations, grouped in a message to the remote TCAP-user.

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0102          |      Parameter Length         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                       Destination Address                     /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0103          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                    Originatiting   Address                    /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0106          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                    Components  present                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0001          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Network Appearance                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0101          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                   Quality of Service                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0104          |      Parameter Length         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                 Application  context  name                    /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0105          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                      User information                         /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0301          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                      Security  Context                        /
      \                                                               \
 
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     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0302          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                        Confidentiality                        /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
        Parameters
           Destination address	         M
           Originating address	         M
           Components present              M(Ind)	
           Network Appearance              O	
           Quality of Service	         O		
           Application context name	  O		
           User information	                O          
           Security Context	                O(A)		
           Confidentiality	                O(A)		
   
3.3.2  Query
The Query request message may be issued prior to passing any component
to the Component sublayer.At the receiving side, the destination 
TCAP-user is informed that a new dialogue starts by means of a Query
indication message.

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0102          |      Parameter Length         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                       Destination Address                     /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0103          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                    Originatiting   Address                    /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0106          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       Components  present                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0506          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Query Type                             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0001          |             Length            |
  
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      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Network Appearance                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0101          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                   Quality of Service                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0104          |      Parameter Length         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /               Application  context  name                      /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0105          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                          User   information                   /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0301          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                      Security  Context                        /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0302          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                        Confidentiality                        /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
        Parameters
        
           Destination address	        M
           Originating address	        M
           Query Type   	               M(A) 
           Components present             M(Ind)	
           Network Appearance             O
           Quality of Service	        O		
           Application context name       O		
           User information	               O		
           Security Context	               O(A)		
           Confidentiality	               O(A)

3.3.3  Conversation

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0503          |             Length            |

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      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                      Conversation Type                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0106          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       Components  present                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0001          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Network Appearance                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0101          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Quality of Service                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0102          |      Parameter Length         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                Application  context  name                     /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0103          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                 Originatiting  Address                        /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0105          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                      User   information                       /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0301          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                      Security  Context                        /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0302          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                          Confidentiality                      /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
        Parameters
        
           Conversation Type 	            M(A) 
           Components present                 M(Ind)	
           Network Appearance                 O		
           Quality of Service	            O	
           	
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           Application context name	     O		
           Originating address	            O		
           User information	                   O		
           Security Context	                   O(A)		
           Confidentiality	                   O(A)	

3.3.4   End

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0106          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       Components  present                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0107          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                    Termination                                |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0001          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Network Appearance                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0101          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                     Quality of Service                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0104          |      Parameter Length         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /               Application  context  name                      /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0105          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                        User   information                     /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0301          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                     Security  Context                         /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0302          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                          Confidentiality                      /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
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        Parameters
        
           Components present               M(Ind)
           Termination                      M(Req)	
           Network Appearance               O		
           Quality of Service	          O		
           Application context name	   O		
           User information	                 O		
           Security Context	                 O(A)		
           Confidentiality	                 O(A)	

3.3.5   U_Abort

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0001          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Network Appearance                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0101          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                   Quality of Service                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0104          |      Parameter Length         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /               Application  context  name                      /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0105          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                       User information                        /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0401          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Abort reason                           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0301          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                      Security  Context                        /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0302          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                         Confidentiality                       /
 
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      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0303          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                 User   Abort  Information                     /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

 
        Parameters

           Network Appearance                O		
           Quality of Service	           O		
           Application context name	    O
           User information	                  O
           Abort Reason		           O(I)		
           Security Context	                  O(A)		
           Confidentiality	                  O(A)
           User Abort Information            O(A)

3.3.6   P_Abort

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0108          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                            P-Abort                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0001          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Network Appearance                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0101          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                   Quality of Service                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  
Parameters

           P-Abort                           M
           Network Appearance                O		
           Quality of Service	           O		
           

3.3.7 Notice

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       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0109          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       Report  cause                           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0001          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Network Appearance                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0103          |      Parameter Length         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                 Originatiting  Address                        /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0102          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                       Destination  Address                    /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Parameters
           
           Report  cause                         M
           Network Appearance                    O		
           Destination address	               O		
           Originating address	               O	      	

3.4 Component Handling(CH) Message
     
     The following section describes the TUA Component handling
   messages and parameter contents.  The general message format
   includes a Common Message Header together with a list of zero or
   more parameters as defined by the Message Type.  All Message Types
   can have attached parameters.

3.4.1  Invoke

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0201          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         Invoke  ID                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0204           |         Length               |
 
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      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                         Operation                             /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0504          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Invoke Type                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0203          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       Last component                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0202          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                             Timeout                           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0402          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                           Class                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0001          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Network Appearance                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0205          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                         Parameters                            /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0208          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                  Correlation   ID                             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     
Parameters

           Invoke ID                                   M
           Operation                                   M
           Invoke Type	                            M(A)
           Last component                              M(Ind)
           Timeout                                     M(Req)
           Class                                       M(I)(Req)
           Network Appearance                          O      
           Parameters                                  O    
           Correlation ID                              O
          
3.4.2  Result

Jianxing  Hou, et al                                        [Page 27]
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       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0201          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                               Invoke  ID                      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0203          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       Last component                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0001          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Network Appearance                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0204          |          Length               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                      Operation                                /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0205          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                          Parameters                           /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0208          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                    Correlation  ID                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
             
Parameters

           Invoke ID                            M
           Last component                       M(Ind)
           Network Appearance                   O	
           Operation                            O
           Parameters                           O
           Correlation ID                       O(A)
          
3.4.3  U_Error

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0201          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       Invoke  ID                              |

Jianxing  Hou, et al                                        [Page 28]
Internet Drift       SS7 TCAP-User Adaptation Layer       April1,2001

 
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0206          |           Length              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                           Error                               /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0203          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                    Last component                             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0001          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Network Appearance                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0205          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                         Parameters                            /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0208          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                    Correlation  ID                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Parameters

           Invoke ID                              M
           Error                                  M
           Last component                         M(Ind)
           Network Appearance                     O           
           Parameters                             O
           Correlation ID                         O(A)
           
3.4.4   Reject

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0207          |         Length                |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       Problem code                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0203          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                      Last component                           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0505          |             Length            |
 
Jianxing  Hou, et al                                        [Page 29]
Internet Drift       SS7 TCAP-User Adaptation Layer       April1,2001

      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                     Reject Type                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0001          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Network Appearance                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0201          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Invoke  ID                             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0208          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                   Correlation   ID                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0205          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                          Parameters                           /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   
Parameters

           Problem code                            M
           Last component                          M(Ind)
           Reject Type                             M(I)
           Network Appearance                      O	   
           Invoke ID                               O
           Correlation   ID                        O(A)           
           Parameters                              O(A)
           

3.4.5   Cancel

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0201          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         Invoke  ID                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0001          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Network Appearance                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Parameters
 
Jianxing  Hou, et al                                        [Page 30]
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           Invoke ID                                   M
           Network Appearance                          O	    

3.4.6   Timer_reset

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0201          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Invoke  ID                             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0001          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Network Appearance                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Parameters

           Invoke ID                                  M
           Network Appearance                         O
	   

3.5 SS7 Signaling Network Management Messages

3.5.1 Destination Unavailable (DUNA)

   In the scope of TUA, this message is covered by the PC state 
indication passed between TCAP and local TCAP-user. The DUNA message is
sent from the SG to all concerned ASPs (servicing TCAP-usersconsidered
local to the SG), when an SS7 destination has become unreachable.  The
TUA-User at the ASP is  expected to stop traffic to the affected 
destination through the SG initiating the DUNA.

   The format for DUNA Message parameters is as follows:

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0005          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                     Affected Point Code                       /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0001          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Network Appearance                     |
 
Jianxing  Hou, et al                                        [Page 31]
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      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0004          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                          Info String                          /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Parameters
     
     Affected Point Code           M
     Network Appearance            O
     Info String                   O

3.5.2 Destination Available (DAVA)

   In the scope of TUA, this message is covered by the PC state
indication passed between TCAP and local TCAP-user. The DAVA message is
sent from the SG to all concerned ASPs (servicing TCAP-users considered
local to the SG) to indicate that an SS7 destination is now reachable.
The ASP TUA-User protocol is expected to resume traffic to the affected
destination through the SG initiating the DAVA.

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0005          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                     Affected Point Code                       /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0001          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Network Appearance                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0004          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                          Info String                          /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Parameters
     
     Affected Point Code           M
     Network Appearance            O
     Info String                   O

3.5.3 SS7 Network Congestion (SCON)

Jianxing  Hou, et al                                        [Page 32]
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   The SCON message can be sent from the SG to all concerned ASPs to
   indicate that the congestion level in the SS7 network to a specified
   destination has changed.

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0010          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       Congestion Level                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x000E          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      \                          Affected PC                          \
      /                                                               /
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0001          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                      Network Appearance                       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0004          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                          info string                          /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Parameters
    
     Congestion Level              M
     Affected PC                   M
     Network Appearance            O
     Info String                   O

3.5.4 Destination User Part Unavailable (DUPU)

   The DUPU message is used in local broadcast procedures (TUA for TCAP
   - TCAP user interface).The format for DUPU Message parameters is as
     follows:

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0009          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                           Cause/User                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0005          |             Length            |
 
Jianxing  Hou, et al                                        [Page 33]
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      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                     Affected Point Code                       /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0001          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Network Appearance                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0004          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                          info string                          /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Parameters
   
     Cause/User                    M
     Affected Point Code           M*
     Network Appearance            O
     Info String                   O

 Note *:    In the DUPU message, the Affected Point Code Parameter
               MUST contain, at most, a single Affected Point Code.

3.6 Application Server Process Maintenance Messages

3.6.1 ASP Up (UP)

   The ASP UP (UP) message is used to indicate to a remote TUA peer
   that the Adaptation layer is up and running.

       0                     1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |            Tag = 0x0109       |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        ASP Capabilities                       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |            Tag = 0x0004       |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                          Info String                          /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Parameters
     ASP Capabilities              O
     Info String                   O

Jianxing  Hou, et al                                        [Page 34]
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3.6.2 ASP Up Ack (UP ACK)

   The ASP UP Ack message is used to acknowledge an ASP-Up message
   received from a remote TUA peer.

       0                     1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |            Tag = 0x0109       |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        ASP Capabilities                       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |            Tag = 0x0004       |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                          Info String                          /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Parameters
     ASP Capabilities              O
     Info String                   O

3.6.3 ASP Down (DN)

   The ASP Down (DN) message is used to indicate to a remote TUA peer
   that the adaptation layer is not running.

       0                     1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |            Tag = 0x000A       |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                             Reason                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |            Tag = 0x0004       |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                          Info String                          /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Parameters
     Reason              M
     Info String         O

3.6.4 ASP Down Ack (DOWN ACK)

Jianxing  Hou, et al                                        [Page 35]
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   The ASP DOWN Ack message is used to acknowledge an ASP-Down message
   received from a remote TUA peer.

       0                     1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |            Tag = 0x000A       |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                             Reason                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |            Tag = 0x0004       |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                          Info String                          /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Parameters
     Reason                        M
     Info String                   O

3.7 ASP Traffic Maintenance Messages

3.7.1 ASP Active (ACTIVE)

   The ASPAC message is sent by an ASP to indicate to a remote TUA peer
   that it is Active and ready to process signaling traffic for a
   particular Application Server

   The format for the ACTIVE message is as follows:

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Tag = 0x000B         |            Length             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       Traffic Mode Type                       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Tag = 0x0006         |            Length             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                       Routing Context                         /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Tag = 0x0004         |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                          Info String                          /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Jianxing  Hou, et al                                        [Page 36]
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   Parameters
     Traffic Mode Type        M
     Routing Context          O
     Info String              O

3.7.2 ASP Active Ack (ACTIVE ACK)

   The ASPAC Ack message is used to acknowledge an ASP-Active message
   received from a remote TUA peer.

   The format for the ACTIVE Ack message is as follows:

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Tag = 0x000B         |            Length             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       Traffic Mode Type                       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Tag = 0x000F         |            Length             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                             SGP  Status                       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Tag = 0x0006         |            Length             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                       Routing Context                         /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Tag = 0x0004         |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                          Info String                          /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Parameters
        Traffic Mode Type     M
        Routing Context       O
        Info String           O

   The format of the Traffic Mode Type and Routing Context parameters
   is the same as for the ASP-Active message.

   The format and description of the optional Info String parameter is
   the same as for the ASP-Active message.

3.7.3  ASP Inactive (INACTIVE)

Jianxing  Hou, et al                                        [Page 37]
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   The INACTIVE message is sent by an ASP to indicate to a remote TUA
   peer that it is no longer processing signaling traffic within a
   particular Application Server.

   The format for the ASPIA message parameters is as follows:

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Tag = 0x0006         |            Length             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                       Routing Context                         /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Tag = 0x0004         |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                          INFO String                          /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Parameters
     Routing Context          O
     INFO String              O

3.7.4 ASP Inactive Ack (INACTIVE ACK)

   The INACTIVE Ack message is used to acknowledge an ASP-Inactive
   message received from a remote TUA peer.

   The format for the INACTIVE Ack message is as follows:

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Tag = 0x0006         |            Length             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                       Routing Context                         /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Tag = 0x0004         |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                          INFO String                          /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Parameters
 
Jianxing  Hou, et al                                        [Page 38]
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     Routing Context     O
     INFO String         O

   The format of the Traffic Mode Type and Routing Context parameters
   is the same as for the ASP-Active message.

   The format and description of the optional Info String parameter is
   the same as for the ASP-Active message.

3.8 Management Messages

   These messages are used for managing TUA .

3.8.1 Error (ERR)

   The ERR message is sent between two TUA peers to indicate an error
   situation.  The Data parameter is optional, possibly used for error
   logging and/or debugging.

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Tag = 0x000C         |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                          Error Code                           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Tag = 0x0007         |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                        Diagnostic Info                        /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Parameters
     Error Code                    M
     Diagnostic Info               O

3.8.2 Notify (NTFY)

   The Notify message used to provide an autonomous indication of TUA
   events to an TUA peer.

       0                     1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Tag = 0x000D         |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Status Type/ID                         |
  
Jianxing  Hou, et al                                        [Page 39]
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      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Tag = 0x0006         |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                       Routing Context                         /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Tag = 0x0004         |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                          Info String                          /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The NTFY message contains the following parameters:

   Parameters
     Status Type/ID                M
     Routing Context               O
     Info String                   O
    
3.9 SGP Traffic Maintenance (SGPTM) Messages
   
3.9.1 SGP Active
    This messages is used to notify ASP that SGP's status is changed.
 
       0                     1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Tag = 0x000F         |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                            SGP Status                         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
 The  message contains the following parameters:

   Parameters
     SGP  Status                 M      
     
3.10 Common Parameters

   These TLV parameters are common across the different adaptation
   layers.

   Parameter Name                     Parameter ID
   ==============                     ============
   Network Appearance                   0x0001
   Not used in TUA                      0x0002
   Not used in TUA                      0x0003

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   Info String                          0x0004
   Affected Point Code                  0x0005
   Routing Context                      0x0006
   Diagnostic Info                      0x0007
   Not used in TUA                      0x0008
   Cause/User                           0x0009
   Reason                               0x000A
   Traffic Mode Type                    0x000B
   Error Code                           0x000C
   Status Type                          0x000D
   Congestion Level                     0x000E
   SGP Status                           0x000F  

3.10.1 Network Appearance

   The Network Appearance parameter identifies the SS7 network context
   for the message, for the purposes of logically separating the
   signaling traffic between the SG and the Application Server Process
   over a common SCTP Association.  An example is where an SG is
   logically partitioned to appear as an element in several different
   national SS7 networks.

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Tag = 0x0001         |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        network appearance                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The Network Appearance implicitly defines the SS7 Point Code format
   used, the SS7 Network Indicator value and SCCP protocol
   type/variant/version used within the SS7 network partition.  Where
   an SG operates in the context of a single SS7 network, or individual
   SCTP associations are dedicated to each SS7 network context, the
   Network Appearance parameter is not required.

   The Network Appearance parameter value is of local significance
   only, coordinated between the SG and ASP.

   Where the optional Network Appearance parameter is present, it must
   be the first parameter in the message as it defines the format of
   the Protocol Data field.

3.10.2 Not used

     Parameter ID 0x02 is not used in TUA.

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3.10.3 Not used

     Parameter ID 0x03 is not used in TUA.

3.10.4 Info String

   The INFO String parameter can carry any meaningful 8-BIT ASCII
   character string along with the message.  Length of the INFO String
   parameter is from 0 to 255 characters.  No procedures are presently
   identified for its use but the INFO String may be used by Operators
   for debugging purposes.

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Tag = 0x0004         |            length             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                          info string                          /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

3.10.5 Affected Point Code

   The Affected Point Code parameter contains one or more Affected
   Destination Point Codes, each a three-octet parameter to allow for
   4-, 16- and 24-bit binary formatted SS7 Point Codes.  Affected Point
   codes that are less than 24-bits, are padded on the left to the 24-
   bit boundary.

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Tag = 0x0005         |            length             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |    Mask       |                 Affected PC 1                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                             . . .                             /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The encoding is shown below for ANSI and ITU Point Code examples.

   ANSI 24-bit Point Code:

       0                   1                   2                   3-->
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 
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      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Mask      |    Network    |    Cluster    |     Member    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                      |MSB-----------------------------------------LSB|

   ITU 14-bit Point Code:

       0                   1                   2                   3-->
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Mask      |0 0 0 0 0 0 0 0 0 0|Zone |     Region    | SP  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                                           |MSB--------------------LSB|

   It is optional to send an Affected Pointe Code parameter with more
   than one Affected PC but it is mandatory to receive it.  All the
   Affected PCs included must be within the same Network Appearance.
   Including multiple Affected PCs may be useful when reception of an
   management message or a linkset event simultaneously affects the
   availability status of a list of destinations at an SG.

   Mask: 8-bits

   The Mask parameter can be used to identify a contiguous range of
   Affected Destination Point Codes, independent of the point code
   format.  Identifying a contiguous range of Affected PCs may be
   useful when reception of an MTP3 management message or a linkset
   event simultaneously affects the availability status of a series of
   destinations at an SG.

   The Mask parameter is an integer representing a bit mask that can be
   applied to the related Affected PC field.  The bit mask identifies
   how many bits of the Affected PC field is significant and which are
   effectively "wild-carded".  For example, a mask of "8" indicates
   that the last eight bits of the PC is "wild-carded".  For an ANSI
   24-bit Affected PC, this is equivalent to signaling that all PCs in
   an ANSI Cluster are unavailable.  A mask of "3" indicates that the
   last three bits of the PC is "wild-carded".  For a 14-bit ITU
   Affected PC, this is equivalent to signaling that an ITU Region is
   unavailable.

3.10.6 Routing Context

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1

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      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Tag = 0x0006         |            length             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                       Routing Context                         /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The Routing Context parameter contains (a list of) 4-byte unsigned
   integers indexing the Application Server traffic that the sending
   ASP is configured/registered to receive.  There is one-to-one
   relationship between an index entry and a SG Routing Key or AS Name.
   Since an AS can only appear in one Network Appearance, the Network
   Appearance parameter is not required in the ASP Active message.

   An Application Server Process may be configured to process traffic
   for more than one logical Application Server.  From the perspective
   of an ASP, a Routing Context defines a range of signaling traffic
   that the ASP is currently configured to receive from the SG.

3.10.7 Diagnostic Information

   The Diagnostic Information can be used to convey any information
   relevant to an error condition, to assist in the identification of
   the error condition.  In the case of an Invalid Network Appearance,
   Adaptation Layer Identifier or Traffic Handling Mode, the Diagnostic
   information includes the received parameter.In the other cases,
   the Diagnostic information may be the first 40 bytes of the
   offending message.

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0007          |            Length             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                     Diagnostic Information*                   /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

3.10.8 Not Used
   Parameter ID 0x08 is not used in TUA.

3.10.9 Cause/User

       0                   1                   2                   3
 
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       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0009          |            Length             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |            Cause              |             User              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Unavailability Cause field: 16-bits (unsigned integer)

   The Unavailability Cause parameter provides the reason for the
   unavailability of the TUA-User.  The valid values for the
   Unavailability Cause parameter are shown in the following table.

            0         Unknown
            1         Unequipped Remote User
            2         Inaccessible Remote User

   User Identity field: 16-bits (unsigned integer)

   The User Identity describes the specific TUA-User that is
   unavailable.  Some of the valid values for the User Identity are
   shown below.

          0 - 2          Reserved by M3UA
          3              SCCP/SUA
          4 - 10         Reserved by M3UA
          11             TCAP/TUA

3.10.10 Reason

   The Reason parameter indicates the reason that the remote TUA
   adaptation layer is unavailable.

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x0009          |            Length             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |            Cause              |             User              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Reason: 32-bit (unsigned integer)

   The valid values for Reason are shown in the following table.

          0         Unspecified

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          1         User Unavailable
          2         Management Blocking
          3         ASP Fault

3.10.11 Traffic Mode Type

   The Traffic Mode Type parameter identifies the traffic mode of
   operation of the ASP within an AS.

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Tag = 0x000B         |             length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                      Traffic Mode Type                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The valid values for Type are shown in the following table.

               1         Over-ride
               2         Load-share
               3         Over-ride (Standby)
               4         Loadshare (Standby)

   Within a Routing Context, Over-ride and Loadshare Types cannot be
   mixed.  The Over-ride value indicates that the ASP is operating in
   Over-ride mode, and the ASP wishes to take over all traffic for an
   Application Server (i.e., primary/back-up operation), over-riding
   any currently active ASP in the AS.  In Load-share mode, the ASP
   wishes to share in the traffic distribution with any other currently
   active ASPs.  The Standby versions of the Over-ride and Loadshare
   Types indicate that the ASP is declaring itself ready to accept
   traffic but leaves it up to the sender as to when the traffic is
   started. Over-ride (Standby) indicates that the traffic sender
   continues to use the currently active ASP until it can no longer
   send/receive traffic (i.e., the currently active ASP transitions to
   Down or Inactive).  At this point the sender may immediately move
   the ASP to Active and commence traffic.  Loadshare (Standby) is
   similar - the sender continues to loadshare to the current ASPs
   until there it is determined that there is insufficient resources in
   the Loadshare group.  When there is insufficient ASPs, the sender
   may immediately move the ASP to Active.

3.10.12 Error Code

       0                   1                   2                   3
 
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      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Tag =0x000C            |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                          Error Code                           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The Error Code parameter indicates the reason for the Error Message.
The Error parameter value can be one of the following values:

        Invalid Version                                0x01
        Invalid Network Appearance                     0x02
        Unexpected Message Class                       0x03
        Invalid Message Type                           0x04
        Unsupported Traffic Handling Mode              0x05
        Unexpected Message                             0x06
        Protocol Error                                 0x07
        Invalid Routing Context                        0x08
        Invalid Stream Identifier                      0x09
        Parameter Field Error                          0x0B
        Unexpected Parameter                           0x0C
        Duplicated Parameter                           0x0D

   The "Invalid Version" error would be sent if a message was received
with an invalid or unsupported version.The Error message would contain
the supported version in the Common header.The Error message could 
optionally provide the supported version in the Diagnostic Information
area.

   The "Invalid Network Appearance" error would be sent by a SG if an
ASP sends a message with an invalid (unconfigured) Network Appearance
value.

   The "Unsupported Traffic Handling Mode" error would be sent by a SG
if an ASP sends an ASP Active with an unsupported Traffic Handling
Mode.An example would be a case in which the SG did not support
load-sharing.

  The "Unexpected Message" error would be sent by an ASP if it received
a message while it was in the Inactive state.

  The "Protocol Error" error would be sent for any protocol anomaly
(i.e. a bogus message).

   The "Invalid Routing Context" error would be sent by a SG if the
routing context cannot be supported, e.g. not unique.

 
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   The "Invalid Stream Identifier" error would be sent if a message
was received on an unexpected SCTP stream (i.e.  a stream that did not
have an Interface Identifier associated with it).

   The "Unexpected Message Class" error would be sent if a message with
an unexpected or unsupported Message Class is received.

   The "Parameter Field Error" would be sent if a message with a
parameter having a wrong length field.

   The "Unexpected Parameter" error would be sent if a message contains
an invalid parameter.

   The "Duplicated Parameter" error would be sent if a message contains
a parameter more than once.

   The Cause parameter can be one of the following values:

          Invalid Version                         0x1
          Invalid Network Appearance              0x2
          Invalid Adaptation Layer Identifier     0x3
          Invalid Message Type                    0x4
          Invalid Traffic Handling Mode           0x5
          Unexpected Message Type                 0x6
          Protocol Error                          0x7
          Invalid Routing Context                 0x8
          Unsupported Message Type                0x9

3.10.13 Status Type

   The Status Type parameter identifies the type of the status that is
   being notified.

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Tag = 0x000D         |             length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Status Type           |            Status ID          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The valid values for Status Type (16 bit unsigned integer) are:

          1     Application Server state change (AS_State_Change)
          2     Other

   The Status ID parameter contains more detailed information for the

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notification, based on the value of the Status Type.

   If the Status Type is AS_STATE_CHANGE, then the Status ID (16 bit
unsigned integer) values are:

          1    reserved
          2    Application Server Inactive (AS-Inactive)
          3    Application Server Active (AS-Active)
          4    Application Server Pending (AS-Pending)

   These notifications are sent from an SG to an ASP upon a change in
status of a particular Application Server. The value reflects the new
state of the Application Server.

   If the Status Type is Other, then the following Status Information
values are defined:

             1    Insufficient ASP resources active in AS
             2    Alternate ASP Active

   These notifications are not based on the SG reporting the state
change of an ASP or AS.  In the Insufficient ASP Resources case,the SG
is indicating to an "Inactive" ASP(s) in the AS that another ASP is 
required in order to handle the load of the AS (Load-sharing mode).
For the Alternate ASP Active case, an ASP is informed when an alternate
ASP transitions to the ASP-Active state in Over-ride mode.

3.10.14 Congestion Level

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Tag = 0x000E          |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       Congestion Level                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Congestion Level field: 8-bits (unsigned integer)

   The Congestion Level will have two different meanings, depending
upon the message it is received with.

   For the SCON message, the Congestion Level field, contains one of
the following values,which are associated with a destination point
code:

            0     No Congestion or Undefined
 
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            1     Congestion Level 1
            2     Congestion Level 2
            3     Congestion Level 3

   The congestion levels are as defined in the national congestion
method in the appropriate MTP recommendation [ITU-MTP], [ANSI-MTP].
For MTP  congestion methods that do not employ congestion levels
(e.g., the ITU international method, the parameter is always
"Undefined"). When an SCON is received at the SG, a TFC message is
generated into the SS7 network.

3.10.15  SGP Status
      
      This Parameter indict
       0                     1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Tag = 0x000F         |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          spare                |           SGP Status          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

SGP Status
      values
        0                          Inactive
        1                          Stangby
        2                          Active
        3-255                      Reserved by IETF    
      
3.11 TUA-Specific parameters

   These TLV parameters are specific to the TUA protocol.

   Parameter Name                     Parameter ID
   ==============                     ============
(For dialogue handling) 
   Quality of Service                   0x0101
   Destination Address                  0x0102
   Originating Address                  0x0103
   Application context name             0x0104
   User information                     0x0105
   Components present                   0x0106
   Termination                          0x0107
   P_Abort                              0x0108
   Report cause                         0x0109
(For component handling ) 
   Invoke ID                            0x0201
 
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   Timeout                              0x0202
   Last component                       0x0203
   Operation                            0x0204
   Parameters                           0x0205
   Error                                0x0206
   Problem code                         0x0207
   Correlation ID                       0x0208

(Only in ANSI)                                
   Security Context                     0x0301
   Confidentiulity                      0x0302
   User Abort information               0x0303
   
(Only in ITU )                                
   Abort reason                         0x0401
   Class                                0x0402
   
(For Common)
   Conversation Type                    0x0503
   Invoke Type                          0x0504
   Reject Type                          0x0505
   Query Type                           0x0506

3.11.1  Quality of Service

   The "Quality of Service" parameters for the connectionless SCCP
network service at present consists of the following:

      "Return Option" - Specifies whether the SCCP "return message 
                        on error" is requested.
      "Sequence Control" - The presence of this parameter indicates the
                          SCCP Class 1 is  requested and when used in a
                          request primitive, explicitly  provides the 
                          information needed to deliver a series of 
                          messages in sequence.

      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |         Tag = 0x0101          |             Length            |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                Spare          | Seq Control   | Return Option |  
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   -  Return Option   
          Bits 1 indicate if or not "return  message on error"

 
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         Values      Description
           0         It  is not necessary to return message on error
           1         It  is  necessary to return message on error
          
         Bits 2-8        are spare and should be coded zero.

    -Sequence  Control 
        The first octet  indicate whether the information needed to 
        deliver in sequence.

         Values      Description
          0         It is not necessary to deliver message in sequence
          1         It is necessary todeliver message in sequence
          2-255     reserved               
 
The second octet  indicate sequence number of the message. 

3.11.2  Destination  Address            
 
       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Tag = 0x0102         |      Parameter Length         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      /                            Address                            /
      \                                                               \
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      
       The format for Destination Address  is as SCCP address's format.
       In ITU,see ITU Q713 chap3.4,In ANSI,see ANSI T1.112.3 chap 3.4.
 
  
3.11.3 Originating Address

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |          Tag = 0x0103       |               Length            |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     /                          address                              /
     \                                                               \
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

The format of this parameter is identical to the Source Address
parameter.

   

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3.11.4   Application context name
   The application context is the identifier of the application context
proposed by the dialogue initiator or by the dialogue responder. An 
application context is an explicitly identified set of application-
service-elements, related options and any other necessary information
for the interworking of application-entities on a dialogue. see Q.771
chap 3.1.2.1.

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Tag = 0x0104         |           Length              |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    /                 Application  context  name                    /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

3.11.5 User information 
      User information which can be exchanged between TCAP users 
      independently from the remote operation service.see Q.771 
      chap 3.1.2.1.

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Tag = 0x0105         |           Length              |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    /                          User information                     /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

3.11.6  Components present

   Components present  indicates whether or not components are present. 
If components are present, then only syntactically valid and opportune
components are delivered to the destination TC-user by TCAP in the same
order they were delivered to TCAP by the source TC-user.see Q.771 
chap3.1.2.1

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Tag = 0x0106         |            Length             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                     spare                     |   present     |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

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present 
              values                 
                0               components are present
                1               components are  not present
                2-255             Spare

3.11.7 Termination
   Termination indicates which scenario is chosen by the TC-user for
the end of the dialogue(prearranged or basic).see Q.771 chap 3.1.2.1.

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Tag = 0x0107         |            Length             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                       spare                   |  Termination  |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Termination
               values                 
                0               prearranged 
                1               basic
                2-255           Spare
         
3.11.8   P_Abort
 
     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Tag = 0x0108         |             Length            |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                            spare              |    P_Abort    |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

P_Abort
   
 (In ITU)
      values
      0                     UNRECOGNIZ_MSG   
      1                     UNRECOGNIZ_TID  
      2                     BADLY_FORMAT    
      3                     INCORRECT_TSCT  
      4                     RESOURCE_LIMIT   
      5                     L_RESOURCE_LIMIT 
      6                     INVALID_DLG_REQ  
      7                     PENDING_EXPIRED  
      8                     BEGIN_EXPIRED   
 
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      9                     INACTIVE_EXPIRED 
      10                    DST_ADDR_UNKNOW 
      11                    NETWORK_ERROR   
      12                    UNRECOGNIZ_DID  
      13                    ABNORMAL_DLGP    
      14                    NO_COMMON_DLGP  
      15-255                spare

 (In ANSI)
      values
      0                     spare
      1                     UNRECOGNIZED_PACKAGE_TYPE    
      2                     INCORRECT_TRANSACTION_PORTION
      3                     BAD_STRUCTURED_TRANSACTION_PORTION
      4                     UNASSIGNED_RESPONDING_TID
      5                     PERMISSION_TO_RELEASE_PROBLEM
      6                     RESOURCE_UNAVAILABLE
      7                     UNRECOGNIZED_DIALOGUE_PORTION_ID
      8                     BAD_STRUCTURED_DIALOGUE_PORTION
      9                     MISSING_DIALOGUE_PORTION
      10                    INCONSISTENT_DIALOGUE_PORTION
      11                    P_ABORT_CAUSES_BUTT
      12-255                spare

3.11.9   Report cause
     It contains information indicating the reason for the exception
report, that the message was returned by the SCCP with the reason as
specified in Recommendation Q.711. This parameter is required for the
TC-NOTICE indication primitive.It is  used only  in ITU,if necessary,
it maybe used in ANSI.

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Tag = 0x0109         |            Length             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                         spare                 | Report cause  |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Report cause

         values   
	    0         no translation for an address of such nature;
	    1         no translation for this specific address;
	    2         subsystem congestion;
	    3         subsystem failure;
            4         unequipped user;

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	    5         MTP failure;
	    6         network congestion;
	    7         SCCP unqualified;
	    8         error in message transport;
	    9         error in local processing;
	    10        destination cannot perform reassembly;
	    11        SCCP failure;
	    12        hop counter violation;
	    13        segmentation not supported;
	    14        segmentation failed.
         15-255    spare

3.11.10 Invoke ID

 It identifies an operation invocation and its result.

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Tag = 0x0201         |            Length             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                    spare                      |     ID        |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

3.11.11 Timeout

It indicates the maximum lifetime of an operation invocation.The unit
of lifetime is second. 

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Tag = 0x0202         |            Length             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                             time                              |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

3.11.12 Last component

    This parameter is used in primitives of the "indication" type only,
to designate the last component of a message. Note that indication of 
the last part of the result of an operation is via the name of the 
primitive.

     0                   1                   2                   3
 

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    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Tag = 0x0203         |            Length             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                    spare                      |    value      |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

value
         values
           0             It is the last component of a message
           1             It is not the last component of a message

3.11.13  Operation
     It identifies the action to be executed by a TC-user on request of
another TC-user.

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0204          |         Length                |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                    spare                      |   type        |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    /                         Operation Code                        /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

type
  (In ITU)
          values
             0                       local
             1                       global operations
             2-255                   spare
   (in ANSI)
          values
             0                       National TCAP
             1                       Private  TCAP

3.11.14 Parameters

     It contains any parameters accompanying an operation,or provided
in reply to an operation.

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Tag = 0x0205         |          Length               |
 
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    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    /                            Parameters                         /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.11.15   Error
     It contains information provided by the TC-user when an operation
returns failure.

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          Tag = 0x0206         |           Length              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                    spare                      |      type     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   /                             Error                             /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

type
        values
(In ITU)
          0                   local  error
          1                   global error
          2-255               spare
(In ANSI)
          0                   National TCAP
          1                   Private  TCAP       
          2-255               spare
                   

3.11.16   Problem code
It identifies the cause for rejecting a component.

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Tag = 0x0207         |           Length              |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |            spare              |   Problem     |     type      |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

type 
   (In ITU)
     values
       0               General Problem
       1               Invoke

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       2               Return Result
       3               Return Error
       4-255           spare
     (In ANSI)
     values
       0               Not used
       1               General
       2               Invoke
       3               Retrun Result
       4               Return Error
       5               Transaction Portion
       6-255           spare                

problem
     For ITU,see Q773  chap4.2.2.6
     For ANSI,seeT1.114.3  chap5.16.2

3.11.17 Correlation ID
      The Correlation ID is assigned to Components sent in response to
 another Component It is mandatory when the received Component had an
 Invoke ID.It is one octet long, if present. In ITU,it is called Linked
 ID.

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Tag = 0x0208         |            Length             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                    spare                      |      ID       |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

3.11.18 Security Context  
      This identifier is coded context specific (in the context of the
dialogue portion sequence).
        
     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Tag = 0x0301         |            Length             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    /                      Security Context                         /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

3.11.19 Confidentiulity

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   Confidentiality Identifier is coded context specific (in the 
 context of the dialogue portion sequence), constructor.

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Tag = 0x0302         |           Length              |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    /                        Confidentiulity                        /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

3.11.20  User Abort information
      This indicates User Specified Information supplied by the TC_user
when it aborts a transaction
     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Tag = 0x0303         |           Length              |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    /                          Information                          /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

3.11.21 Abort reason
      This parameter indicates whether a dialogue is aborted because
the received application context name is not supported and no 
alternative one can be proposed (abort reason =application context not
supported) or because of any other user problem (abort reason =user
specific).
 
     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0401          |            Length             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                      spare                    |    reason     |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

reason
         values
             0               application context not supported
             1               user specific
             2-255           spare

3.11.22  class

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  It indicates class of operations

     0                   1                   2                   3
     
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0402          |            Length             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                    spare                      |     class     |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

class
          values
            0                spare
            1                Both success and failure are reported
            2                Only failure is reported   
            3                Only success is reported.      
            4                Neither success, nor failure is reported.   
            5-255            spare

3.11.23 Conversation Type
       It indicates the type of Conversation
     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Tag = 0x0503         |           Length              |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          spare                                |     Type      |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-Type
       value
         0       Conversation Without Permission
         1       Conversation With Permission
         2-255   spare
            
3.11.24 Invoke Type
       It indicates the type of Invoke Message
     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Tag = 0x0504         |           Length              |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          spare                                |     Type      |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    
-Type
       value
 
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         0               Invoke Not Last
         1               Invoke Last
         2-255           spare
         
3.11.25 Reject Type
       It indicates the type of reject
     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Tag = 0x0505         |           Length              |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |            spare                              |     Type      |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+    

-Type
       value
         0               TC_U_REJECT 
         1               TC_L_REJECT 
         2               TC_R_REJECT
         3-255           spare

3.11.26 Query Type
       It indicates the type of query.
     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Tag = 0x0506         |           Length              |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |             spare                             |       Type    |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

-Type
       value
         0       Query Without Permission 
         1       Query With Permission
         2-255   spare

 
4 Procedures

   The TUA layer needs to respond to various local primitives it
receives rom other layers as well as the messages that it receives from
the peer TUA layers.  This section describes the TUA procedures in
response to these events.

4.1 TCAP _ TUA Interworking at the SG

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 On the SG, the TCAP routing or interworking function determines that
the message must be sent to an AS via the TUA stack, based on 
information in the incoming message. The TUA outgoing mapping function
identifies the appropriate Application Server(AS)and selects an active
ASP from the list of ASPs servicing this AS. The appropriate ASP can be
determined based on the routing information   in the incoming message,
local load sharing information, etc.The appropriate TUA message is then
constructed and sent to the appropriate endpoint, via the correct SCTP 
association and stream.

4.2 Primitives received from the local TUA-User

   These support the TUA transport of TCAP-User/TCAP boundary 
primitives. The same services as supported by TCAP are to be provided 
by TUA. The TCAP-Users at the SG should be able to  use the same 
primitive interface to TCAP/TUA without any  changes. The TCAP-TUA
interworking function takes care of  selecting the appropriate stack.

   The TUA needs to setup and maintain the appropriate SCTP association
to the selected endpoint. TUA also manages the usage of SCTP streams.
The address information passed by the TUA-user at an ASP must contain:
   - a valid SS7 address to reach a destination in the SS7 network via
     the appropriate SCTP association to a SG
   - a valid IP address/hostname to reach another ASP in the IP network
     via the appropriate SCTP association.
   
4.3 Layer Management Procedures

    On receiving primitives from the local Layer Management,the TUA
layer will take the requested action and provide a response to Layer 
Management.

   An M-SCTP-ESTABLISH request from Layer Management will initiate the
establishment of an SCTP association. An M-SCTP-ESTABLISH confirm will
be sent to Layer Management when the initiated association set-up is 
complete. An M-SCTP-ESTABLISH indication is sent upon successful 
completion of an incoming SCTP association set-up from a peer TUA node.

   An M-SCTP-RELEASE request from Layer Management initiates the 
tear-down of an SCTP association. An M-SCTP-RELEASE confirm is sent to
Layer Management when the association tear-down is complete. An M- SCCP
-RELEASE indication is sent to Layer Management upon successful 
tear-down of an SCTP association initiated by a peer TUA.

   An M-SCTP-STATUS request supports a Layer Management query of the 
local status of a particular SCTP association. The TUA responds with 
the association status in an M-SCTP-STATUS confirm. No peer TUA 

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protocol is invoked.

   An M-ASP-STATUS request supports a Layer Management query of the
 status of a particular local or remote ASP. The TUA responds with an
 M-ASP-STATUS confirm. No peer TUA protocol is invoked.

   An M-AS-STATUS request supports a Layer Management query of the 
status of a particular AS.The TUA responds with an M-AS-STATUS confirm.
No peer TUA protocol is invoked.

   M-ASP-UP,-DOWN,-ACTIVE and _INACTIVE request primitives allow Layer
Management at an IPSP to force state changes. Upon successful 
completion, a corresponding confirm primitive is issued by TUA to the
Layer Management.If the invocation is unsuccessful,an Error indication
is provided.

   Layer Management is informed by TUA Management about AS/ASP state 
changes with the corresponding indications. It is also informed of 
received NTFY or ERR messages.

4.4 TUA Management Procedures

    This functionality comprises the handling of AS/ASP state and
traffic management messages, TUA peer management messages, SCTP 
notifications and the interface with local Layer Management.These 
procedures support the TUA management of SCTP Associations and ASP 
paths between SGs and ASPs.

4.4.1 AS and ASP State and Traffic Management

   The TUA layer on SG needs to maintain the state of each connected
ASP,as a way to manage the traffic to these ASPs and the (logical) ASs
they service.In particular at a  SG, the state of each connected ASP is
needed as input to the SG routing function.

4.4.1.1  ASP States

   The state of each ASP is maintained in the TUA layer in the SG or 
IPSP. The state of an ASP changes due to events. The events include:
   - ASP Management messages(ASP-Up,ASP-Down,ASP-Active,ASP-Inactive)
   - SCTP Communication Down Notification (SCTP CDI)
       
   The state of the ASP within each AS is important in particular for 
the routing function at the SG, in order to direct traffic for a 
specific routing key (AS) to the appropriate ASP.

   At an ASP, if it is connected to a set of redundant SGPs, this set

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can also be seen as an AS handling all traffic destined for the SS7
network.
   The ASP state transition diagram is shown in Figure 4. The possible
 states of an ASP are:

   ASP-DOWN: The Application Server Process is unavailable. Initially
 all ASPs will be in this state.

   ASP-UP: The Application Server Process is available but application
 traffic is not possible. The ASP can only handle management messages.

   ASP-ACTIVE: The Application Server Process is available and 
application traffic is possible. Whether traffic will be directed to
this ASP depends on the Traffic Mode Type (over-ride, loadshare with or
without Standby option).

  ASP-STANDBY: The remote TUA peer at the ASP is available and ready to
receive application traffic at any time (for a particular Routing 
Context or set of Routing Contexts).  In this state the ASP can be sent
any non-Data TUA messages.

    SCTP CDI: The local SCTP layer's SHUTDOWN COMPLETE notification or
COMMUNICATION LOST notification. The shutdown of an SCTP association 
may have been requested by local Layer Management.

                                   +-----------------+
                                   |   ASP-ACTIVE    |
            +----------------------|      or         |      
            |                      |  ASP-STANDBY*   | 
            |                      +-----------------+
            |                          ^     |
            |                   ASP    |     | ASP
            |                   Active |     | Inactive
            |                          |     v
            |                      +-------------+
            |                      |             |
            |                      |   ASP-UP    |
            |                      +-------------+             
            |                          ^    |                  
   ASP Down |                     ASP  |    | ASP Down /       
   SCTP CDI |                     Up   |    | SCTP CDI         
            |                          |    v                 
            |                      +-------------+             
            |                      |             |             
            +--------------------->|  ASP-DOWN   |
                                   |             |
                                   +-------------+

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                  Figure 4: ASP State Transition Diagram

*Note: ASP-ACTIVE and ASP-STANDBY differ only in whether the ASP is 
currently receiving Data traffic within the AS.

4.4.1.2  AS States

       The state of the AS is maintained in the TUA layer on the SG.

       The state of an AS changes due to events. These events include:
        - ASP state changes : when the first ASP within an AS goes UP
          or  ACTIVE, or when the last ASP within an AS goes DOWN or
          INACTIVE
        - Recovery Timer expiry

   The possible states of an AS are:

   AS-DOWN: The Application Server is unavailable.  This state implies
that all related ASPs are in the ASP-DOWN state for this AS.Initially
the AS will be in this state.

  AS-UP: The Application Server is available but no application traffic
is possible (i.e. one or more related ASPs are in the ASP-UP state, but
none in the ASP-ACTIVE state).

     AS-ACTIVE: The Application Server is available and application 
traffic is possible. This state implies that at least one ASP is in the
ASP-ACTIVE state.

   AS-PENDING: An active ASP has transitioned from active to inactive 
or down and it was the last remaining active ASP in the AS. A recovery
timer T(r) will be started and all incoming SCN messages will be queued
by the SG. If an ASP becomes active before T(r) expires, the AS will 
move to AS-ACTIVE state and all the queued messages will be sent to the
active ASP.If T(r) expires before an ASP becomes active, the SG stops 
queuing messages and discards all previously queued messages. The AS 
will move to AS-UP if at least one ASP is in ASP-UP state, otherwise it
will move to AS-DOWN state.

         +----------+   one ASP trans to ACTIVE   +-------------+
         |          |---------------------------->|             |
         |  AS-UP   |                             |  AS-ACTIVE  |
         |          |<---                         |             |
         +----------+    \                        +-------------+
            ^   |         \ Tr Expiry,                ^    |
            |   |          \ at least one             |    |
 
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            |   |           \ ASP in UP               |    |
            |   |            \                        |    |
            |   |             \                       |    |
            |   |              \                      |    |
    one ASP |   | all ASP       \            one ASP  |    | Last ACT.
    trans   |   | trans to       \           trans to |    | asp trans
    to UP   |   | DOWN            -------\   ACTIVE   |    | to UP or
            |   |                         \           |    | DOWN
            |   |                          \          |    |
            |   |                           \         |    |
            |   |                            \        |    |
            |   v                             \       |    v
         +----------+                          \  +-------------+
         |          |                           --|             |
         | AS-DOWN  |                             | AS-PENDING  |
         |          |                             |  (queueing) |
         |          |<----------------------------|             |
         +----------+       Tr Expiry no ASP      +-------------+
                            in UP state

         Tr = Recovery Timer

                    Figure 5: AS State Transition Diagram

 
4.4.2  AS/ASP Management procedures

   Once an SCTP association is established between SG and  ASP, ASP
must issue an ASP-UP message.All ASP Maintenance messages are sent on
a sequenced stream to ensure ordering.  SCTP stream '0' is used.

4.4.2.1 ASP-Up

    After an ASP has successfully established an SCTP association to an
SG,the SG waits for the ASP to send an ASP-Up message, indicating that
the ASP TUA peer is available.  The ASP is always the initiator of the 
ASP-Up exchange.  This action MAY be initiated at the ASP by an M-ASP 
UP request primitive from Layer Management or may be initiated 
automatically by an TUA management function.

When an ASP-Up message is received at an SG and internally the remote 
ASP is in the "Down" state and not considered locked-out for local 
management reasons, the SG marks the remote ASP as "Inactive" and 
informs Layer Management with an M-ASP-Up indication primitive.If the
SG knows, via current configuration data, which Application Servers the 

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ASP is configured to operate in, it can update the ASP status to 
"Inactive" in each AS that it is a member.  Alternatively, the SG may 
move the ASP into a pool of Inactive ASPs available for future 
activation in Application Server(s) denoted in the subsequent ASP-
Active Routing Contexts.The SG responds with an ASP-Up Ack message in 
acknowledgement.  The SG sends an ASP-Up Ack message in response to a 
received ASP-Up message even if the ASP is already marked as "Inactive" 
at the SG.  

    If for any local reason (e.g., management lock-out) the SG cannot 
respond with an ASP-Up Ack, the SG responds to an ASP-Up with an ASP-
Down Ack message with Reason "Management Blocking".  

   At the ASP, the ASP-Up Ack message received is not acknowledged.
Layer Management is informed with an M-ASP UP confirm primitive .

   When the ASP sends an ASP-Up message it starts timer T(ack).  If the 
ASP does not receive a response to an ASP-Up within T(ack),the ASP MAY 
restart T(ack) and resend ASP-Up messages until it receives an ASP-Up 
Ack message.  T(ack) is provisionable, with a default of 2 seconds.  
Alternatively, retransmission of ASP-Up messages may be put under 
control of Layer Management.  In this method, expiry of T(ack) results 
in a M-ASP-Up confirmation carrying a negative indication.  

   The ASP must wait for the ASP-Up Ack message before sending any
other TUA messages (e.g., ASPAC).  If the SG receives any other TUA
messages before an ASP Up is received, the SG should discard them.

     If an ASP-Up is received and internally the remote ASP is in the 
"Active" or "Standby" state, an Error ("Unexpected Message) is returned 
and the remote ASP state is not changed.

   If an ASP-Up is received and internally the remote ASP is already in 
the "Inactive" state,and ASP-Up Ack is returned and no action is taken.

4.4.2.2 ASP-Down

   The ASP will send an ASP-Down to an SG when the ASP wishes to be 
removed from service in all Application Servers that it is a member and 
no longer receive any TUA traffic or management messages.  This action 
MAY be initiated at the ASP by an M-ASP DOWN request primitive from 
Layer Management or may be initiated automatically by an TUA management
function.   

   Whether the ASP is permanently removed from any AS is a function of 
configuration management.

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   The SG marks the ASP as "Down", informs Layer Management with an 
M-ASP Down indication primitive, and returns an ASP-Down Ack message
to the ASP if one of the following events occur:

    - an ASP-Down message is received from the ASP,
    - another ASPM message is received from the ASP and the SG has  
      locked out the ASP for management reasons.
 
    The SG sends an ASP-Down Ack message in response to a received 
ASP-Down message from the ASP even if the ASP is already marked as
"Down" at the SG.  

    At the ASP, the ASP-Down Ack message received is not acknowledged. 
Layer Management is informed with an M-ASP Down confirm primitive.

    When the ASP sends an ASP-Down it starts timer T(ack).  If the ASP
does not receive a response to an ASP-Down within T(ack), the ASP MAY 
restart T(ack) and resend ASP-Down messages  until it receives an ASP-
Down Ack message.T(ack) is provisionable, with a default of 2 seconds.
Alternatively, retransmission of ASP-Down messages may be put under
control of Layer Management.In this method, expiry of T(ack)results in
a M-ASP-Down confirmation carrying a negative indication. 

4.4.2.3 TUA Version Control

    If an ASP-Up message with an unsupported version is received, the 
receiving end responds with an Error message, indicating the version 
the receiving node supports and notifies Layer Management.

    This is useful when protocol version upgrades are being performed
in a network. A node upgraded to a newer version should support the 
older versions used on other nodes it is communicating with.  Because
ASPs initiate the ASP-Up procedure it is assumed that the Error message 
would normally come from the SG.

4.4.2.4 ASP-Active

    Anytime after the ASP has received an ASP-Up Ack from the SG or 
IPSP,the ASP sends an ASP-Active (ASPAC) to the SG indicating that the
ASP is ready to start processing traffic.This action MAY be initiated
at the ASP by an M-ASP Active request primitive from Layer Management
or may be initiated automatically by an TUA management function.In the
case where an ASP wishes to process the traffic for more than one 
Application Server across a common SCTP association, the ASPAC contains 
a list of one or more Routing Contexts to indicate for which 
Application Servers the ASPAC applies. It is not necessary for the ASP 
to include all Routing Contexts of interest in the initial ASPAC 

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message, thus becoming active in all Routing Contexts at the same time.    
Multiple ASPAC messages MAY be used to activate within the Application 
Servers independently.  In the case where an ASP-Active message does 
not contain a Routing Context parameter, the receiver must know, via 
configuration data, which Application Server(s) the ASP is a member.

    When an ASP Active (ASPAC) message is received, the SG or IPSP
responds with an ASPAC Ack message(with the same Type value contained
in the received APAC), acknowledging that the ASPAC was received and, 
depending on the ASPAC Type value, moves the ASP to the "Active" or 
"Standby" state within the associated Application Server(s). Layer 
Management is informed with an ASP-Active indication primitive. If the 
SG or IPSP receives any Data messages before an ASPAC is received, the 
SG or IPSP should discard them.  By sending an ASPAC Ack, the SG or 
IPSP is now ready to receive and send traffic for the related Routing 
Contexts.  The ASP MUST not send Data messages before receiving an 
ASPAC Ack.

     Multiple ASPAC Ack messages MAY be used in response to an ASPAC 
containing multiple Routing Contexts, allowing the SG or IPSP to 
independently Ack for different (sets of) Routing Contexts.  The SG or 
IPSP sends an Error ("Invalid Routing Context") message for each 
invalid or un-configured Routing Context value in a received ASPAC 
message. 

     The SG MUST send an ASP-Active Ack message in response to a
received ASP-Active message from the ASP and the ASP is already marked
as "Active" at the SG.  

    At the ASP,the ASP-Active Ack message received is not acknowledged. 
Layer Management is informed with an M-ASP Active confirm primitive.

    When the ASP sends an ASP-Active it starts timer T(ack).If the ASP 
does not receive a response to an ASP-Active within T(ack), the ASP MAY 
restart T(ack) and resend ASP-Active messages until it receives an ASP-
Active Ack message.  T(ack) is provisionable, with a default of 2 
seconds.  Alternatively, retransmission of ASP-Active messages may be 
put under control of Layer Management.  In this method, expiry of 
T(ack) results in a M-ASP-Active confirmation carrying a negative 
indication.  

    There are four modes of Application Server traffic handling in the
SG TUA Over-ride, Over-ride (Standby), Loadshare and Load-share 
(Standby).  The Traffic Mode Type parameter in the ASPAC message 
indicates the traffic handling mode used in a particular Application 
Server. If the SG determines that the mode indicated in an ASPAC is 
unsupported or incompatible with the mode currently configured for the 

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AS, the SG responds with an Error message indicating "Unsupported /
Invalid Traffic Handling Mode".  If the Traffic Handling mode of the 
Application Server is not already known via configuration data, then 
the Traffic handling mode indicated in the first ASPAC message causing 
the transition of the Application Server state to "Active" MAY be used 
to set the mode.

   In the case of an Over-ride mode AS,reception of an ASPAC message at 
an SG causes the redirection of all traffic for the AS to the ASP that 
sent the ASPAC.  Any previously active ASP in the AS is now considered 
Inactive and will no longer receive traffic from the SG within the AS.  
The SG or IPSP sends a Notify (Alternate ASP-Active) to the previously 
active ASP in the AS, after stopping all traffic to that ASP.  

  In the case of Over-ride (Standby) mode the traffic is not started to 
the ASP until the previously active ASP transitions to "Inactive or 
"Down" state.  At this point the ASP that sent the Over-Ride (Standby) 
ASPAC is moved to the Active state and the traffic is redirected.  A 
second ASP-Active Ack message with a new Traffic Mode Type ("Over-
ride", previously "Over-ride(Standby)") is sent to the ASP. A Notify 
(Alternate ASP-Active) message is not sent in this case.

  In the case of a Load-share mode AS,reception of an ASPAC message at 
an SG or IPSP causes the direction of traffic to the ASP sending the 
ASPAC, in addition to all the other ASPs that are currently active in 
the AS.  The algorithm at the SG for load-sharing traffic within an AS
to all the active ASPs is implementation dependent.  The algorithm 
could, for example be round-robin or based on information in the Data 
message (e.g., such as the SLS, SCCP SSN, TCAP DID value).  

    An SG or IPSP, upon reception of an ASPAC for the first ASP in a 
Loadshare AS, MAY choose not to direct traffic to a newly active ASP 
until it determines that there are sufficient resources to handle the 
expected load (e.g., until there are sufficient ASPs "Active" in the 
AS).

   In the case of Load-share (Standby) mode,the traffic is not started
to the ASP until the SG or IPSP determines that there are insufficient 
resources available in the AS.  This is likely when one of the active 
load-sharing ASPs transitions to the "Inactive" or "Down" state.  At 
this point the ASP that sent the Load-share (Standby) ASPAC is moved to 
the Active state and traffic is started.  A second ASP-Active Ack 
message with a new Traffic Mode Type ("Load-share" - previously 
"Loadshare(Standby)") is sent to the ASP. A Notify ("Insufficient ASP 
resources active in AS ") message is not sent in this case.

    All ASPs within a load-sharing mode AS must be able to handle any 

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traffic within the AS, in order to accommodate any potential fail-over 
or rebalancing of the offered load.

4.4.2.5 ASP Inactive

    When an ASP wishes to withdraw from receiving traffic within an AS,
the ASP sends an ASP Inactive (ASPIA) to the SG or IPSP.This action MAY 
be initiated at the ASP by an M-ASP INACTIVE request primitive from 
Layer Management or may be initiated automatically by an TUA 
management function.   In the case where an ASP is processing the 
traffic for more than one Application Server across a common SCTP 
association, the ASPIA contains one or more Routing Contexts to 
indicate for which Application Servers the ASPIA applies.  In the case 
where an ASP-Inactive message does not contain a Routing Context 
parameter, the receiver must know, via configuration data, which 
Application Servers the ASP is a member and move the ASP to the 
"Inactive" state in each AS.

    In the case of an Over-ride mode AS, where another ASP has already 
taken over the traffic within the AS with an Over-ride ASPAC, the ASP 
that sends the ASPIA is already considered by the SG to be "Inactive".  
An ASPIA Ack message is sent to the ASP, after ensuring that all 
traffic is stopped to the ASP. 

    In the case of a Load-share mode AS, the SG moves the ASP to the 
"Inactive" state and the AS traffic is re-allocated across the 
remaining "active" ASPs per the load-sharing algorithm currently used
within the AS.  A NTFY(Insufficient ASP resources active in AS) may be 
sent to all inactive ASPs, if required.  However, if a Loadshare
(Standby) ASP is available, it may be now immediately included in the 
loadshare group and a Notify message is not sent.  An ASPIA Ack message 
is sent to the ASP after all traffic is halted and Layer Management is 
informed with an ASP-INACTIVE indication primitive.

     Multiple ASPIA Ack messages MAY be used in response to an ASPIA 
containing multiple Routing Contexts, allowing the SG or IPSP to 
independently Ack for different (sets of) Routing Contexts.  The SG or 
IPSP sends an Error ("Invalid Routing Context") message for each 
invalid or un-configured Routing Context value in a received ASPIA 
message.

     The SG MUST send an ASP-Inactive Ack message in response to a 
received ASP-Inactive message from the ASP and the ASP is already 
marked as "Inactive" at the SG.  

At the ASP, the ASP-INACTIVE Ack message received is not acknowledged. 
Layer Management is informed with an M-ASP INACTIVE confirm primitive.  

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When the ASP sends an ASP-Inactive it starts timer T(ack).  If the ASP 
does not receive a response to an ASP-Inactive within T(ack), the ASP 
MAY restart T(ack) and resend ASP-Inactive messages  until it receives 
an ASP-Inactive Ack message.  T(ack) is provisionable, with a default 
of 2 seconds.  Alternatively, retransmission of ASP-Inactive messages 
may be put under control of Layer Management.  In this method, expiry 
of T(ack) results in a M-ASP-Inactive confirmation carrying a negative 
indication.  

If no other ASPs are "Active" or "Standby" in the Application Server, 
the SG sends a NTFY(AS-Pending) to all inactive ASPs of the AS and 
either discards all incoming messages for the AS or starts buffering 
the incoming messages for T(r)seconds, after which messages will be 
discarded.  T(r) is configurable by the network operator.  If the SG 
receives an ASPAC from an ASP in the AS before expiry of T(r), the 
buffered traffic is directed to the ASP and the timer is cancelled. If 
T(r) expires, the AS is moved to the "Inactive" state.

4.4.3 SGP Mangement Procedures

4.4.3.1 SGP Status
    There are three possible statuses as follow:  
    SGP-INACTIVE: The remote TUA peer at the SGP is available (and the
related SCTP association is up) but application traffic is stopped.

    SGP-ACTIVE: The remote TUA peer at the SGP is available and 
application traffic is active .

    SGP-STANDBY: The remote TUA peer at the ASP is available and ready
to receive application traffic at any time .

4.4.3.2 SGP Mangement 
   When SGP receives an ASP Active message from ASP,it sends an Active 
Ack message to ASP as response.In the message,it tell ASP it's status.
When Asp receives this message,it determines the SGP's Traffic Handling
Mode.
   When the SGP's Traffic Handling Mode is Over-ride,if ASP detects the
active SGP is unavailable, it selects a standby SGP and set it's status
to active,it changes former active SGP's status to standby.When an ASP 
receives a SGP Active message from a SGP,if the SGP's status at the ASP
is standby,the ASP sets the SGP's status to active and changs the 
former active SGP's status to standby. 

4.4.4 TUA peer management messages

4.4.4.1 Notify

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   A NTFY message reflecting a change in the AS state is sent to all
   ASPs in the AS, except those in the "Down" state, with appropriate
   Status Type/ID.

   In the case where a NTFY (AS-Pending) message is sent by an SG that
   now has no active ASPs to service the traffic, or a NTFY
   (Insufficient ASPs) is sent in the Loadshare mode, the NTFY does not
   explicitly force the ASP(s) receiving the message to become active.
   The ASPs remain in control of what (and when) action is taken.

4.4.4.2 Error

   The ERR message is used to signal invalid protocol behaviour.

5 Examples of TUA Procedures

5.1 Establishment of Association and Traffic between SGPs and ASPs

5.1.1.1 Single ASP in an Application Server ("1+0" sparing)

This scenario shows the example TUA message flows for the 
establishment of traffic between an SG and an ASP, where only one ASP 
is configured within an AS (no backup).  It is assumed that the SCTP 
association is already set-up.

             SG                              ASP
              |                                |
              |<-------------ASP Up------------|
              |-----------ASP-Up Ack---------->|
              |                                | 
              |<------- ASP Active-------------|  
              |-----ASP Active Ack------------>|      
              |                                |

5.1.1.2 Two ASPs in Application Server ("1+1" sparing)

This scenario shows the example TUA message flows for the 
establishment of traffic between an SG and two ASPs in the same 
Application Server, where ASP1 is configured to be "active" and ASP2 a 
"standby" in the event of communication failure or the withdrawal from 
service of ASP1.  ASP2 may act as a hot, warm, or cold standby 
depending on the extent to which ASP1 and ASP2 share call/transaction 
state or can communicate call state under failure/withdrawal events.  
The example message flow is the same whether the ASP-Active messages 
are Over-ride or Load-share mode although typically this example would 
use an Over-ride mode. 

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      SG                        ASP1                        ASP2
        |                         |                          |
        |<--------ASP Up----------|                          | 
        |-------ASP-Up Ack------->|                          |
        |                         |                          |
        |<-----------------------------ASP Up----------------|
        |-----------------------------ASP-Up Ack------------>|
        |                         |                          | 
        |                         |                          |
        |<-------ASP Active-------|                          | 
        |------ASP-Active Ack---->|                          | 
        |                         |                          |

5.1.1.3 Two ASPs in an Application Server ("1+1" sparing, load-sharing 
case)
This scenario shows the example TUA message flows for the 
establishment of traffic between an SG and two ASPs in the same 
Application Server, where the two ASPs are brought to "active" and
load-share the traffic load.In this case, one ASP is sufficient to 
handle the total traffic load.   

       SG                       ASP1                       ASP2
        |                         |                          |
        |<---------ASP Up---------|                          | 
        |--------ASP-Up Ack------>|                          |
        |                         |                          |
        |<------------------------------ASP Up---------------|
        |-----------------------------ASP Up Ack------------>|
        |                         |                          | 
        |                         |                          |
        |<--ASP Active -----------|                          | 
        |-----ASP-Active Ack----->|                          | 
        |                         |                          |
        |<----------------------------ASP Active ------------| 
        |-------------------------------ASP-Active Ack------>| 
        |                         |                          |

5.1.1.4 Three ASPs in an Application Server ("n+k" sparing, load-sharing 
case) 

This scenario shows the example TUA message flows for the 
establishment of traffic between an SG and three ASPs in the same 
Application Server, where two of the ASPs are brought to "active" and 
share the load. In this case, a minimum of two ASPs are required to 

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handle the total traffic load (2+1 sparing). 

 
   SG                  ASP1                 ASP2                ASP3 
    |                    |                   |                   |
    |<------ASP Up-------|                   |                   | 
    |-----ASP-Up Ack---->|                   |                   |
    |                    |                   |                   |
    |<--------------------------ASP Up-------|                   |
    |-------------------------ASP-Up Ack---->|                   |
    |                    |                   |                   |
    |<---------------------------------------------ASP Up--------|
    |---------------------------------------------ASP-Up Ack---->|
    |                    |                   |                   | 
    |                    |                   |                   |
    |<--ASP Act ---------|                   |                   | 
    |----ASP-Act Ack---->|                   |                   | 
    |                    |                   |                   |
    |<--------------------ASP Act  ----------|                   | 
    |-----------------------ASP-Act Ack----->|                   | 
    |                    |                   |                   |

5.1.2 ASP Traffic Fail-over Examples

5.1.2.1 (1+1 Sparing, withdrawal of ASP, Back-up Over-ride) 

 ASP1 withdraws from  service:

       SG                       ASP1                       ASP2 
        |                         |                          |
        |<-----ASP Inactive-------|                          |
        |----ASP Inactive Ack---->|                          |
        |-----------------------NTFY(ASP-Inact.)(Optional)-->| 
        |                         |                          | 
        |<------------------------------ ASP Active----------| 
        |------------------------------ASP-Active Ack------->| 
        |                                                    |

Note: If the SG detects loss of the TUA peer (TUA heartbeat loss or 
detection of SCTP failure), the initial SG-ASP1 ASP Inactive message 
exchange would not occur.

5.1.2.2 (1+1 Sparing, Back-up Over-ride)

ASP2 wishes to  over-ride ASP1 and take over the traffic:

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       SG                       ASP1                       ASP2 
        |                         |                          | 
        |<------------------------------ ASP Active----------| 
        |-------------------------------ASP-Active Ack------>|
        |----NTFY(Alt ASP-Act)--->| 
        |                         |                          | 

5.1.2.3 (n+k Sparing, Load-sharing case, withdrawal of ASP)

ASP1 withdraws from  service:

   SG                  ASP1                 ASP2                 ASP3 
    |                    |                   |                   |
    |<----ASP Inact.-----|                   |                   | 
    |---ASP-Inact Ack--->|                   |                   |
    |                    |                   |                   | 
    |---------------------------------NTFY(Ins. ASPs)(Optional)->| 
    |                    |                   |                   |
    |<-----------------------------------------ASP Act ----------| 
    |-------------------------------------------ASP Act (Ack)--->|
    |                    |                   |                   |

The Notify message to ASP3 is optional, as well as the ASP-Active from 
ASP3.  The optional Notify can only occur if the SG maintains knowledge 
of the minimum ASP resources required - for example if the SG knows 
that "n+k" = "2+1" for a load-share AS and "n" currently equals "1". 

Note: If the SG detects loss of the ASP1 TUA peer (TUA heartbeat loss 
or detection of SCTP failure), the first SG-ASP1 ASP Inactive message 
exchange would not occur.  

5.1.3 TCAP/TCAP-User Service Translation Examples
When the TUA layer on the ASP has a DH message to send to the SG, it
will do the following:

  - Determine the correct SGP

  - Find the SCTP association to the chosen SGP

  - Determine the correct stream in the SCTP association based on
    the DID

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  - Build the DH message, fill TUA Message Header, fill Common Header

  - Send the DH message to the remote TUA peer in the SG, over the
    SCTP association

When the TUA layer on the SG has a DH message to send to the ASP, it
will do the following:

  - Determine the AS 

  - Determine the Active ASP (SCTP association) within the AS

  - Determine the correct stream in the SCTP association based on
    the DID

  - Build the DH message, fill in TUA Message Header, fill in
    Common Header

  - Send the DH message to the remote TUA peer in the ASP, over the
    SCTP association

An example of the message flows for establishing a dialogue service
is shown below.An active association between ASP and SG is established
(Section 5.1) prior to the following message flows.

             SG                             ASP

                        <----------- Invoke Request
                        <----------- Query(Begin) Request
                        
 Conversation(Continue)
      Indication        ---------->
  Result Indication     ---------->
  
                        <----------- Invoke  Request
                        <----------- Conversation(Continue) Request
                            .
                            .
                            .                            
  End(respone)Indication ----------->
                        
      Result Indication ----------->

                     
An example of the message flows for a failed attempt to establish a
dialogue on the signaling channel is shown below.  In this case, the
gateway has a problem with its physical connection ,

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so it cannot establish a dialogue on the signaling channel.

 
           SG                             ASP

                        <----------- Invoke Request 
                        <----------- Query(Begin) Request
                        
     Abort Indication   ---------->

5.2 IP-IP Architecture

   The sequences below outline logical steps for a variety of scenarios
   within an IP-IP architecture.  Please note that these scenarios
   cover a Primary/Backup configuration.  Where there is a load-sharing
   configuration then the AS can declare availability when 1 ASP issues
   ASPAC but can only declare unavailability when all ASPs have issued
   ASPIA.

5.2.1 Establishment of TUA connectivity

   The following shows an example establishment of TUA connectivity.
   In this example, each IP SP consists of a Management Instance (MI)
   and two ASPs.  The Management Instance handles the address mapping
   mechanisms and monitors the states of the remote peer.  For
   simplicity, the Management Instances and ASPs are considered as a
   separate entity.  This is not a requirement, as they can be co-
   located with an ASP.

   The following must be established before TUA traffic can flow. A
   connectionless flow is shown for simplicity.

   Each node is configured (via MIB, for example) with the connections
   that need to be setup

   IP SEP A                                                  IP SEP B
   ASP-a1     ASP-a2     MI a             MI b       ASP-b2    ASP-b1
   (Primary) (Backup)                               (Backup) (Primary)

               Establish SCTP Connectivity

                         |-- Est. SCTP Ass.--|

   |------ Establish SCTP Association -------|
   |------------- Establish SCTP Association -------------|
   |------------------ Establish SCTP Association ------------------|

 
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              |--- Establish SCTP Assoc. ----|
              |------- Establish SCTP Association --------|
              |------------ Establish SCTP Association -------------|

                         |-- Establish SCTP Association -|
                         |------- Establish SCTP Association ------|

               Establish TUA Connectivity

   +---------------ASP Up------------------->
   <---------------ASP Up Ack---------------+

              +------------ASP Up----------->
              <------------ASP Up Ack-------+

                        <--------------ASP Up-------------+
                        +--------------ASP Up Ack--------->

                        <----------------ASP Up---------------------+
                        +----------------ASP Up Ack----------------->

   +---------------ASP Act------------------>
   <---------------ASP Act Ack--------------+

                        <----------------ASP Act--------------------+
                        +----------------ASP Act Ack---------------->

   Traffic can now flow directly between ASPs.

   +-------------------------------TCAP_User Message------------------>

5.2.2 Failover scenarios

   The following sequences address failover of ASP

5.2.2.1 Successful ASP Failover scenario

   The following is an example of a successful failover scenario, where
   there is a failover from ASP-a1 to ASP-a2, i.e. Primary to Backup.
   Since data transfer passes directly between peer ASPs, ASP-b1 is
   notified of the failover of ASP-a1 and must buffer outgoing data
   messages until ASP-a2 becomes available.

   IP SEP A                                                  IP SEP B
   ASP-a1     ASP-a2     MI a             MI b       ASP-b2    ASP-b1
   (Primary) (Backup)                               (Backup) (Primary)

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   +--------------ASP Inact----------------->
   <--------------ASP Inact Ack-------------+

              <----NTFY (ASP-a1 Inactive)---+

              +----------ASP Act------------>
              <----------ASP Act Ack--------+

5.2.2.2 Unsuccessful ASP Failover scenario

   The sequence is the same as 5.2.2.1 except that, since the backup
   fails to come in then, the Notify messages declaring the
   availability of the backup are not sent. 
 
6 Security

6.1 Introduction

   TUA is designed to carry signaling messages for telephony services.
   As such, TUA must involve the security needs of several parties: the
   end users of the services; the network providers and the
   applications involved.  Additional security requirements may come
   from local regulation.  While having some overlapping security
   needs, any security solution should fulfill all of the different
   parties' needs.

6.2 Threats

   There is no quick fix, one-size-fits-all solution for security.  As
   a transport protocol, TUA has the following security objectives:

    * Availability of reliable and timely user data transport.
    * Integrity of user data transport.
    * Confidentiality of user data.

   TUA runs on top of SCTP.  SCTP provides certain transport related
   security features, such as:

    * Blind Denial of Service Attacks
    * Flooding
    * Masquerade
    * Improper Monopolization of Services

   When TUA is running in professionally managed corporate or service
   provider network, it is reasonable to expect that this network
   includes an appropriate security policy framework. The "Site
   Security Handbook" [RFC 2196] should be consulted for guidance.

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   When the network in which TUA runs in involves more than one party,
   it may not be reasonable to expect that all parties have implemented
   security in a sufficient manner. End-to-end security should be the
   goal, therefore, it is recommended that IPSEC is used to ensure
   confidentiality of user payload.  Consult [RFC 2409] for more
   information on configuring IPSEC services.

6.3 Protecting Confidentiality

   Particularly for mobile users, the requirement for confidentiality
   may include the masking of IP addresses and ports.  In this case
   application level encryption is not sufficient; IPSEC ESP should be
   used instead. Regardless of which level performs the encryption, the
   IPSEC ISAKMP service should be used for key management.

7 IANA Considerations

7.1 SCTP Payload Protocol ID

   A request will be made to IANA to assign SCTP Payload Protocol IDs.
   A Payload ID for the TUA will be registered.

   The Payload ID is included in each SCTP data chunk, to indicate
   which protocol SCTP is carrying. This Payload ID is not directly
   used by SCTP but may be used by certain network entities to identify
   the type of information being carried in this DATA chunk.

   It is assumed that the Payload ID for TUA will be 8.

7.2 Protocol Extensions

   This protocol may also be extended through IANA in three ways:
    -- through definition of additional message classes,
    -- through definition of additional message types, and
    -- through definition of additional message parameters.

   The definition and use of new message classes, types and parameters
   is an integral part of SIGTRAN adaptation layers.  Thus, these
   extensions are assigned by IANA through an IETF Consensus action as
   defined in [RFC2434].

   The proposed extension must in no way adversely affect the general
   working of the protocol.

7.2.1 IETF Defined Message Classes

   The documentation for a new message class MUST include the following
 
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   information:
   (a) A long and short name for the message class;
   (b) A detailed description of the purpose of the message class.

7.2.2 IETF Defined Message Types

   Documentation of the message type MUST contain the following
   information:

   (a) A long and short name for the new message type;
   (b) A detailed description of the structure of the message.
   (c) A detailed definition and description of intended use of each
       field within the message.
   (d) A detailed procedural description of the use of the new message
       type within the operation of the protocol.
   (e) A detailed description of error conditions when receiving this
       message type.

   When an implementation receives a message type which it does not
   support, it MUST respond with an Error (ERR) message, with an Error
   Code = Unsupported Message Type.

7.2.3 IETF-defined TLV Parameter Extension

   Documentation of the message parameter MUST contain the following
   information:

   (a) Name of the parameter type.
   (b) Detailed description of the structure of the parameter field.
       This structure MUST conform to the general type-length-value
       format described earlier in the document.
   (c) Detailed definition of each component of the parameter value.
   (d) Detailed description of the intended use of this parameter type,
       and an indication of whether and under what circumstances
       multiple instances of this parameter type may be found within
       the same message type.

8 Timer Values

     Tr                                      2 seconds

9 Acknowledgements
  The authors would like to thank John Loughney , Greg Sidebottom ,
Zujian Li and Yi Zhang for their insightful comments and suggestions.

10 Authors' Addresses

  Jianxing Hou
 
Jianxing  Hou, et al                                        [Page 83]
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  Kefa Road, Science-Based Industrial Park,
  Nanshan District,Shenzhen 518057 China
  Email: hjxing@huawei.com

  Ming Lin
  Kefa Road, Science-Based Industrial Park,
  Nanshan District,Shenzhen 518057 China
  Email: mlin@huawei.com

  
11 References

   [2719]         RFC 2719, "Framework Architecture for Signaling
                  Transport"

   [ITU SCCP]     ITU-T Recommendations Q.711-714, 'Signaling System
                  No. 7 (SS7) - Signaling Connection Control Part
                  (SCCP)'

   [ANSI SCCP]    ANSI T1.112 'Signaling System Number 7 - Signaling
                  Connection Control Part'

   [ITU TCAP]     ITU-T Recommendation Q.771-775 'Signaling System No.
                  7 SS7) - Transaction Capabilities (TCAP)

   [ANSI TCAP]    ANSI T1.114 'Signaling System Number 7 - Transaction
                  Capabilities Application Part'

   [SCTP]         RFC 2960 "Stream Control Transport Protocol" R.
                  Stewart, et. Al. November 2000.

   [M3UA]         MTP3-User Adaptation Layer <draft-ietf-sigtran-m3ua-
                  05.txt>, Decemenber 2000, Work in Progress.
     
   [SUA]          SS7 SCCP-User Adaptation Layer<draft-ietf-sigtran-sua
                  -05.txt>,February 2001,Work in Progress.

   [2401]         RFC 2401, "Security Architecture for the Internet
                  Protocol", S. Kent, R. Atkinson, November 1998.

   [2196]         RFC 2196, "Site Security Handbook", B. Fraser Ed.,
                  September 1997.

   [E.164-DNS]    RFC 2916 "E.164 number and DNS", P. Faltstrom,
                  September 2000.

   [RFC2434]      RFC 2434 "Guidelines for Writing an IANA
   
   Jianxing  Hou, et al                                        [Page 84]
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                  Considerations Section in RFCs", T. Narten, H.
                  Alvestrand, October 1998.

   [ITU-MTP]      ITU-T Recommendations Q.701-Q.705, 'Signalling System
                  No. 7 (SS7) - Message Transfer Part (MTP)'

   [ANSI-MTP]     ANSI T1.111 'Signaling System Number 7 - Message
                  Transfer Part'



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