Signalling Connection Control Part: Difference between revisions

Revision as of 18:06, 19 June 2008

Revision as of 18:11, 19 June 2008

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** ''Address Indicator coded as national'' (the Address Indicator is treated as international if not specified)

==ClassesProtocol of serviceclasses==

SCCP provides 5 classes of serviceprotocol to its applications:

* '''Class 0''': Basic connectionless

* '''Class 1''': Sequenced connectionless

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===Class 0: Basic connectionless===

The SCCP Class 0 serviceprotocol class is the most basic of the SCCP transportsprotocol classes. Network Service Data Units passed by higher layers to the SCCP in the originating node are delivered by the SCCP to higher layers in the destination node. They are transferred independently of each other. Therefore, they may be delivered to the SCCP user out-of-sequence. Thus, this protocol class corresponds to a pure [[connectionless protocol|connectionless network service]]. As a connectionless protocol, no transport-levelnetwork dialogconnection is established between the sender and the receiver.

===Class 1: Sequenced connectionless===

SCCP Class 1 builds on the capabilities of Class 0, with the addition of a sequence control parameter in the NSDU which allows the SCCP User to instruct the SCCP that a given stream of messages should be delivered in sequence. Therefore, Protocol Class 1 corresponds to an enhanced connectionless serviceprotocol with assurances of in-sequence delivery.

===Class 2: Basic connection-oriented===

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===Class 3: Flow control connection oriented===

Class 3 service builds upon Class 2, but also allows for expedited (urgent) messages to be sent and received, and for errors in sequencing (segment re-assembly) to be detected and for SCCP to restart a connection should this occur.

==Transport over IP Networks==