SCTP refers to Stream Control Transmission Protocol which is used above the IP layer Protocols . In short term I will say SCTP is a layer 4 protocol and IPv4 and IPv6 , Appletalk are the layer 3 protocols . We can compare the SCTP with TCP , Transmission Control Protocol is also a layer 4 protocol but they differs…
Again SCTP is Stream Control Transmission Protocol , why I am repeating SCTP because It should be clear from its derivation , that it controls the stream of messages . Even TCP can control the data stream , So what’s there in SCTP and not in TCP ? using TCP can form only one connection between its peered endpoint users but using SCTP any application can form multiple connection between peered endpoints . This is the best thing in SCTP , the enduser like you and me doesn’t need to worry during the troubleshooting of one connection , the other streams can provide you the application. SCTP contains of some sequence numbers to bundle the message , like(
TSN — Transmission Seq. Number ‘It is of 32bits ’
SSN — Stream Seq. Number ‘It is also of 32 bits’ ). Sequence Numbers are used for CRC32 check(cyclic redundancy check). SCTP supports multihoming also which means same it can make many connections between two endusers.
SCTP consists of some COOKIE , like (ECHOED_COOKIE , SHUTDOWN_PENDING , SHUTDOWN , etc.) to remember the message source and destination . SCTP uses 4-way handshake so it double checks the destination before connection . Selective ACK (SACK) is used in SCTP to gather the information of echoed_cookie , that which endpoint user is echoing and so there it needs to be send and then it transfers the CHUNKS data to the Lower Protocol Layers(LPL).
In SCTP Bundeling is the carrying of small message and Fragmentation is the division of large messages.
Chunks in SCTP is a seperate brief topic ,will cover for next some story .
Thanks…
