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PGW2200 - SIGTRAN Protcol Support





This document describes the SIGTRAN Protocol support on PGW2200. The Cisco PGW 2200 can use Sigtran Protocol, MTP3 User Adaptation (M3UA) and SCCP User Adaption (SUA) to communicate with Cisco ITPs. Cisco IP Transfer Point (ITP) act as the signaling gateway for the Cisco PGW 2200 to Interconnect with the STP (Signaling Transfer Point) Network in PSTN.


This document was generated from the following thread: PGW2200 - Full SIGTRAN Support, to Help Users to know about the SIGTRAN support on PGW2200 SoftSwitch.







The Cisco PGW 2200 Softswitch is a carrier-class call agent that performs the signaling and call-control tasks—such as digit analysis, routing, and circuit selection—within the public switched telephone network (PSTN) gateway infrastructure. The Cisco PGW 2200 gives service providers the ability to smoothly route voice and data calls between the PSTN and newer packet networks.


Cisco PGW 2200 Softswitch interfaced with the Signaling System 7 (SS7) network through a pair of SS7 link termination devices (SLTs) and iSLT. Although serviceable, these SLTs had limited scalability, flexibility, features, and support for open standards. These limitations have been addressed with the addition of the Cisco IP Transfer Point (ITP) as the signaling gateway for the Cisco PGW 2200.


The Cisco ITP solves these limitations with proven technology and a carrier-class system. It supports capabilities that include signaling transfer point (STP), signaling transport over IP and ATM, and signaling gateway for nextgeneration end nodes such as service switching point (SSP) and service control point (SCP). Cisco ITP is certified by Telcordia as an ANSI STP, is completely based on open standards, and provides STP-class availability. Cisco ITP is offered on multiple platforms and can scale from 4 to 800 links.







Cisco ITP uses open industry standards for traditional SS7 over time-division multiplexing (TDM) links, as well as for next-generation signaling over ATM (MTP3b) and IP (Signaling Transport [Sigtran]). In addition, Cisco ITP has been successfully tested to interoperate with equipment from 18 other vendors using Sigtran protocols.


Cisco ITP supports only the following signaling standards shown in Table. It supports SS7 Signtran M2PA, M3UA Protocols.





MTP (1, 2, 3)

ITU-T Q.701-Q.709 White 1996 (interworks with Blue). ANSI T1.111-1996, China, Japan

Signaling Connection Control Part


ITU-T Q.711-Q.719 White 1996 (interworks with Blue). ANSI T1.112-1996, China, Japan

High-speed links (HSLs)

ITU E1: Q.2140, Q.2110, Q.2210, Q.2144

ANSI T1: GR-2878, I.363, I.361

Stream Control Transmission Protocol



IETF RFC 3309: SCTP Checksum Change

MTP2 Peer-to-Peer Adaptation Layer


IETF Sigtran SS7 M2PA Draft Standard, March 2, 2001

MTP3 User Adaptation


IETF RFC3332: Sigtran SS7 M3UA

SCCP-User Adaptation


IETF Sigtran SS7 SUA Draft Version 16







PGW2200 as Signaling Gateway

Operating as the signaling gateway for the Cisco PGW 2200, the Cisco ITP uses Sigtran M3UA/SCTP/IP between the Cisco ITP and Cisco PGW 2200. To the SS7 network, the ITP uses SS7/TDM, HSL (SS7oATM), or M2PA/SCTP/IP depending on that service provider’s requirements.


SS7 & SIGTRAN Protocol Stack




MTP2-User Peer-to-Peer Adaptation Layer(M2PA)

The M2PA protocol supports the transport of Signaling System Number 7 (SS7) Message Transfer Part (MTP) Level 3 signaling messages over Internet Protocol (IP) using the services of the Stream Control Transmission Protocol (SCTP). M2PA is also used between SS7 Signaling Points using the MTP Level 3 protocol. The SS7 Signaling Points may also use standard SS7 links using the SS7 MTP Level 2 to provide transport of MTP Level 3 signaling messages.


Stream Control Transmission Protocol (SCTP)

The SCTP is designed to transport PSTN signalling messages over IP networks, but is capable of broader applications. SCTP is an application-level datagram transfer protocol operating on top of an unreliable datagram service such as UDP.


MTP3 User Adaptation Layer(M3UA)

The M3UA protocol supports the transport of any SS7 MTP3-User signalling (such as ISUP and SCCP messages) over IP, using the services of the Stream Control Transmission Protocol (SCTP). The protocol is used for communication between a Signalling Gateway (SG) and a Media Gateway Controller (MGC) or IP-resident database.


Signalling Connection Control Part User Adaptation Layer (SUA)

The SUA protocol details the delivery of SCCP-user messages (MAP & CAP over TCAP, RANAP, etc.) 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. This protocol can also support transport of SCCP-user messages between two endpoints wholly contained within an IP network.



Related Information

PGW Soft Switch and ITP


About SIGTRAN Protocol