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An Introduction to SCTP…..

March 15, 2010

The Stream Control Transmission Protocol (SCTP) is an IP transport protocol. It resides at an equivalent level with TCP , and provides a reliable transport service , ensuring that data is transported across the network without error, and in sequence. It is designed to transport Public Switched Telephone Network (PSTN) signalling messages over IP networks, but is capable of broader applications.

SCTP employs a session-oriented mechanism (similar to TCP) for transmission of data. A relationship is established between the endpoints of SCTP associations prior to data transfer , and this relationship is maintained untill all data transmission has been successfully completed.

There are many good features in SCTP , the most important ones are:-

1. Multi-stream capability.

2. A broader concept for connecting endpoints ( similar to , and more useful than , TCP connection) known as ‘association’.

3. Multi-hoaming support.

4. Path and peer failure detection.

Multi Hoaming.

When a peer is multi-homed , one of the IP addresses is selected as the ‘primary destination address’. All data will be destined to this IP, by default. When a failure of a primary address is detected , the sender selects an alternate primary address until the link is restored or the user initiates a change in the primary address.

Assoc shutdown.

Even in shutdown procedures , SCTP has some significant advantages over TCP. For instance , SCTP implements a graceful close of an association by exchanging three messages. These messages acknowledge that both endpoints will cease in their transmissions of data. This allows no room for  ‘half open’ connections ( In TCP , a ‘half open’ connections happens when one endpoint that continues to send data though the peer endpoint is no longer transmitting data).

Reference:

http://www.sctp.org

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