PDF of this tutorialDescription of SIGTRAN Working Group
SIGTRAN (Signaling Transport) is a working group within the IETF standard organization. Its primary purpose is to address the transport of packet-based public switched telephone network (PSTN) signaling over IP networks, taking into account the functional and performance requirements of the PSTN signaling. In order to interwork with the PSTN, IP networks need to transport signaling such as integrated service digital line (ISDN) (e.g. Q.931) or SS7 (e.g. ISDN user part (ISUP), SCCP, and so on) messages between IP nodes such as a signaling gateway (SG), a media gateway controller (MGC), a media gateway (MG), or an IP–based database. The SIGTRAN working group specific goals are:
- Functional and Performance Requirements—The working group produced several informational requests for comment (RFC), identifying functionality and performance requirements to support signaling over IP networks. Signaling messages (especially SS7) have a very stringent loss and delay requirements in the existing telephone networks that must to be adhered to.
- Transport Issues—The working group produced a "standard track" RFC, which defines the transport of signaling protocols using a newly defined transport protocol, based on the requirements identified above.
SIGTRAN Protocol Architecture (RFC 2719)
The architecture that has been defined by SIGTRAN work group consist 3 components:
- A standard IP.
- A common signaling transport protocol—A protocol that supports a common set of reliable transport functions for signaling transport. In particular, SCTP is a new transport protocol that has been defined by the IETF.
- An adaptation sub-layer that supports specific primitives, such as management indications, required by a particular signaling application protocol. Several new adaptation sub-layer protocols have been defined by the IETF: M2PA, M2UA, M3UA, SUA, and IUA. Only one protocol has to be implemented at a given time.
Figure 2. SIGTRAN Protocol Stack Model
