Signalling Connection Control Part: Difference between revisions

Revision as of 01:35, 29 March 2011

Revision as of 20:42, 30 March 2011

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The '''SignallingSignaling Connection Control Part''' ('''SCCP''') is a [[network layer]]<ref>[http://www.itu.int/rec/T-REC-Q.1400/en/ ITU-T Recommendation Q.1400].</ref> protocol that provides extended [[routing]], [[flow control]], segmentation, [[connection-oriented|connection-orientation]], and [[error correction]] facilities in [[Signaling System 7]] telecommunications networks. SCCP relies on the services of [[Message Transfer Part|MTP]] for basic routing and error detection.

==Published specification==

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* '''Global title indicator'''

** ''No Global Title''

** ''Global Title includes Translation Type (TT), Numbering Plan IndiciatorIndicator (NPI) and Type of Number (TON)''

** ''Global Title includes Translation Type only''

* '''Routing indicator'''

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The connectionless protocol classes provide the capabilities needed to transfer one Network Service Data Unit (NSDU) in the "data" field of an XUDT, LUDT or UDT message. When one connectionless message is not sufficient to convey the user data contained in one NSDU, a segmenting/reassembly function for protocol classes 0 and 1 is provided. In this case, the SCCP at the originating node or in a relay node provides segmentation of the information into multiple segments prior to transfer in the "data" field of XUDT (or as a network option LUDT) messages. At the destination node, the NSDU is reassembled.

The connection-oriented protocol classes (protocol classes 2 and 3) provide the means to set up signallingsignaling connections in order to exchange a number of related NSDUs. The connection-oriented protocol classes also provide a segmenting and reassembling capability. If an NSDU is longer than 255 octets, it is split into multiple segments at the originating node, prior to transfer in the "data" field of DT messages. Each segment is less than or equal to 255 octets. At the destination node, the NSDU is reassembled.<ref name="q714">[http://www.itu.int/rec/T-REC-Q.714/en ITU-T Recommendation Q.714] - SignallingSignaling connection control part procedures</ref>

===Class 0: Basic connectionless===

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In the [[SIGTRAN]] suite of protocols, there are two primary methods of transporting SCCP applications across [[Internet Protocol]] networks: SCCP can be transported indirectly using the [[M3UA|''MTP level 3 User Adaptation'' protocol (M3UA)]], a protocol which provides support for users of [[Message Transfer Part|MTP-3]]—including SCCP. Alternatively, SCCP applications can operate directly over the [[SUA|''SCCP User Adaptation'' protocol (SUA)]] which is a form of modified SCCP designed specifically for use in IP networking.

[[ITU-T]] also provides for the transport of SCCP users over [[Internet Protocol]] using the ''Generic SignallingSignaling Transport'' service specified in [http://www.itu.int/rec/T-REC-Q.2150.0/en/ Q.2150.0], the ''signallingsignaling transport converter'' for [[Stream Control Transmission Protocol|SCTP]] specified in [http://www.itu.int/rec/T-REC-Q.2150.3/en/ Q.2150.3] and a specialized ''Transport-Independent SignallingSignaling Connection Control Part'' (TI-SCCP) specified in [http://www.itu.int/rec/T-REC-Q.2220/en/ T-REC-Q.2220].

TI-SCCP can also be used with the ''Generic SignallingSignaling Transport'' adapted for [[Message Transfer Part|MTP3]] and MTP3b as described in [http://www.itu.int/rec/T-REC-Q.2150.1/en/ Q.2150.1], or adapted for [[SSCOP]] or [[SSCOPMCE]] as described in [http://www.itu.int/rec/T-REC-Q.2150.2/en/ Q.2150.2].

== References ==