STREAMS Design

The figure provides an overview of the STREAMS design for SS7. The STREAMS OpenSS7 stack is built, from the top down, of the following components:

TCAP - Transaction Capabilities Application Part

This interface is responsible for providing the services of the Transaction Capabilities Application Part (TCAP) Transacation Sub-Layer (TR) to a TR-User and the services of the TCAP Transaction Component Sublayer (TC) to a TC-User. It is fashioned after the NPI connection-oriented service with additional support for multiple transaction handling.

Three TR-Providers are available as multiplexing drivers in the OpenSS7 stack:

• SS7 SS7 TCAP-TR,
• SIGTRAN TUA, and
• TR test drivers.

One TC-Provider is available as a moudle in the OpenSS7 stack:

• SS7 TCAP-TC.

ISUP - ISDN User Part

This interface is responsible for providing the services of the ISDN User Part to an ISUP-User. It is fashioned after the NPI connection-oriented service.

Three ISUP-Providers are available as multiplexing drivers in the OpenSS7 stack:

• SS7 ISUP,
• SIGTRAN M3UA, and
• ISUP test drivers.

SCCP - Signalling Connection Control Part

This interface is reponsible for providing the services of the Signalling Connection Control Part (SCCP) to an SCCP-User. It is fashioned after the NPI connection-less and connection-oriented services.

Three SCCP-Providers are available as multiplexing drivers in the OpenSS7 stack:

• SS7 SCCP,
• SIGTRAN SUA, and
• SCCP test drivers.

MTP - Message Transfer Part

This interface is responsible for providing the services of the Message Transfer Part (MTP) Level 3 to an MTP-User. It is fashioned after the NPI connection-less service.

Three MTP-Providers are available as multiplexing drivers in the OpenSS7 stack:

• SS7 MTP,
• SIGTRAN M3UA, and
• MTP test drivers.

SLS - Signalling Link Set

This interface is responsible for providing the services of the Signalling Link Set at an SLS-User. It is fashioned after the NPI connection-oriented service.

Several MTP-Providers are avaliable as multiplexing drivers in the OpenSS7 stack:

• SS7 MTP Linkset,
• SIGTRAN M3UA IPSP,
• MTP Linkset test drivers.

SL - Signalling Link

This interface is responsible for providing the services of the Signalling Link at an SL-User. It is fashioned after the DLPI.

One SL-Provider is available as a multiplexing driver:

• SS7 MTP Link, which supports automatic allocation of Signaling Terminals and Signalling Data Links.

Several SL-Providers are available as a modules:

• SS7 MTP Link, which provides SS7 Level 2 state machine support to SDT drivers;
• SS7 MTP3b, which provides SS7 Level 2 support for SSCOP providers;
• SIGTRAN M2PA, which provides SS7 Level 2 support for SCTP providers; and
• SS7/IP which provides SS7 Level 2 support for TLI providers.

One SL-Provier is available as a multiplexing driver:

• SIGTRAN M2UA, which proivders SS7 Level 2 support for SCTP providers.

Several SL-Providers are available as drivers in the OpenSS7 stack for specific hardware:

• ACB56,
• CPC 388,
• others.

SDT - Signalling (Data) Terminal

This interface is responsible for providing the services of the Signalling Data Terminal/Link at an SDT-User. It is fashioned after the CDI.

Each component is laid out as illustrated in the diagram. Some modules must fan-out downstream (and are multiplexors) and some modules fan-out upstream. Multiplexor modules include the Message Transfer Part (MTP) and the Signalling Link Set (SLS).

Each module and multiplexor in the stack is completely independent of the specific hardware which is being used at the driver level. Each protocol modules provides the capability of a stream-head interface for applications at that level (except perhaps at the SDTI level which is performance sensitive).