The document introduces Sigtran, a protocol suite that provides reliable signaling transport for telephony systems, specifically for SS7 protocols over IP networks. It contrasts the SS7 signaling system with the Sigtran protocol stack, highlighting the benefits of the Stream Control Transmission Protocol (SCTP) in terms of flexibility and redundancy. As traffic demands increase, Sigtran offers a solution to alleviate capacity issues in PSTN networks by transitioning to IP infrastructure.

1. SIGTRAN - An
Introduction
Tareque Hossain

2. SS7 & SIGTRAN
! SS7
! Stands for Signaling System No. 7
! A set of telephony signaling protocols which are used to
set up public switched telephone network calls
throughout the world
! SIGTRAN
! Stands for Signaling Transport
! An IETF task force that defined the specifications for a
protocol family to provide reliable datagram service and
user layer adaptation (UA) for Signaling System 7 (SS7)
& ISDN protocols over IP

3. Comparison of SS7 & IP Stack
INAP
HTTP
TCAP
TCP
SCCP
IP
MTP3
DLL
MTP2
Ethernet
MTP1
MTP: Message Transfer Part
SCCP: Signalling Connection Control Part
TCAP: Transaction Capabilities Application Part
INAP: Intelligent Network Application Part

4. SIGTRAN Protocol Stack
TCAP
SCCP
MTP3
ISDN
M3UA
M2UA
M2PA
SUA
IUA
SCTP
IP
M3UA: MTP3 User Adaptation Layer
M2PA: MTP2 User Peer-to-Peer Adaptation Layer
SUA: SCCP User Adaptation Layer
IUA: ISDN User Adaptation Layer
SCTP: Stream Control Transmission Protocol

5. SCTP
! A new transport protocol with time sensitive signaling
in mind
! Flexible enough for general use
! SCTP can use multi-homed endpoints for redundancy
as opposed to TCP strictly connecting 2 endpoints
! TCP is byte streamed, application is responsible for
structuring data. SCTP is message oriented, defining
structured frames of data at transport layer
! Provides multi-streaming capability: data is split into
multiple streams, each independently sequenced

6. SS7/ SIGTRAN Network Architecture
PSTN
Phone
MGC
MGC
SSP
IP
Network
STP
STP
SG
SG
IP
Phone
SCP
SSP
MG
MG
SoftSwitch
PSTN
Phone
SG: Signaling Gateway MGC: Media Gateway Controller STP: Service Transfer Point
MG: Media Gateway SCP: Service Control Point SSP: Service Switching Point

7. Future of SIGTRAN
! Traffic increased by Local Number Portability & SMS
has pushed SS7 networks beyond capacity
! SIGTRAN allows PSTN network to offload traffic to
IP networks
! PSTN infrastructure is many times larger and far
reaching than IP networks
! SIGTRAN will last as long as PSTN networks last
! Questions? Comments?