SIGTRAN is the name of a group of telecommunication protocols created for the interaction of traditional telephony and VoIP . The name is derived from the words signaling and transport was given by the Internet Engineering Task Force (IETF) working group, which is developing specifications for a protocol family that provides reliable datagram service and user-level adaptation for Channel 7 System (SS7) and ISDN . SIGTRAN Protocols is an extension of the SS7 family of protocols. They support the same applications and call control paradigms as SS7, but use the Internet Protocol ( IP ) for addressing and are transmitted via SCTP . The working group at the IETF closed in March 2009 as having completed its task. [one]
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SIGTRAN Protocols
The M2PA, M2UA, M3UA , SCTP, TALI, IUA, SUA, V5UA protocols describe the transmission of packets of various protocols of the OKS-7 stack over an IP network. For example, the M3UA provides MTP-3 layer adaptation for higher layer signaling protocols ( ISUP and SCCP ). For example, when transmitting signaling messages within the framework of one basic call, ISUP is “sure” that it uses MTP services and a signaling channel to manage voice channels ( time slots used for media), in reality, all this is virtual, since the M3UA protocol “replaces” MTP- 3 and messages are transmitted over the SCTP transport protocol between nodes with IP addresses.
List of protocols with references to standards
- SCTP - Stream Control Transmission Protocol - provides reliable transportation of SIGTRAN group protocols over an IP network. Protocol Specifications: RFC 2960 , RFC 3873 , RFC 4166 , RFC 4960 .
- IUA - ISDN User Adaptation - ISDN User Adaptation Protocol provides the SCTP transport adaptation layer for the uninterrupted transmission of Q.921 user messages and the service interface over an IP network. Examples of protocols that can be transmitted over the IUA are Q.931 and QSIG . Protocol Specifications: RFC 4233 , RFC 4129 (DPNSS / DASS 2), RFC 5133 .
- M2UA - Message Transfer Part 2 User Adaptation Layer - SCTP adaptation protocol for the uninterrupted transmission of MTP layer 2 user messages and the service interface over an IP network. Specification: RFC 3331 .
- M2PA - Message Transfer Part 2 User Peer-to-Peer Adaptation Layer - the protocol provides an SCTP adaptation layer to provide an SS7 MTP signaling channel over an IP network. The differences between M2PA and M2UA are described in section 1.9 of the main protocol specification, RFC 4165 .
- M3UA - Message Transfer Part 3 User Adaptation Layer - the protocol provides an SCTP adaptation layer for the uninterrupted transit or peering of MTP layer 3 user messages and the service interface in an IP network. Specification: RFC 4666 .
- SUA - Signaling Connection Control Part User Adaptation - The SCCP adaptation protocol provides the SCTP adaptation layer for seamless transit or peering of user messages and the service interface of the signaling control part via an IP network. Specification: RFC 3868 .
- V5UA - V5 User Adaptation - Provides an SCTP adaptation layer for the seamless transmission of V5.2 user messages and the service interface over an IP network. This protocol is an IUA variant. Specification: RFC 3807 .
Protocol and Adaptation Scheme
| Protocols OKS-7 | TCAP | |||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| V5.2 | MTP3 | MTP3 | ISUP | SCCP | DSS1 | TCAP | ||||||||||||||
| SIGTRAN | V5UA | M2UA | M2pa | M3ua | IUA | SUA | ||||||||||||||
| Computer network | SCTP | |||||||||||||||||||
| IP | ||||||||||||||||||||
SCTP Transport
The most significant and well-known protocol (including beyond the scope of telephony applications) is the transport protocol SCTP .
The main advantage over other popular transport protocols ( TCP and UDP ) is the presence of several possible routes that are used simultaneously
History and Documents
IETF's decisions regarding SIGTRAN were significantly influenced by the opinion of telecommunications engineers regarding the use of new protocols for adapting VoIP networks to PSTNs, with particular attention to signaling applications. Recently, SCTP has found application beyond its original purpose, where the best of reliable datagram services is required .
SIGTRAN was published in RFC 2719 , titled "Architectural Signaling Framework for Transport. RFC 2719 also defines the concept of a signaling gateway (SG) that translates CCS SS7 messages to SIGTRAN. Implemented on various network elements, including switches, SG functions can provide significant value to existing signaling protocols over a common network channel using the capabilities of SS7 associations and IP-related delivery performance.