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Showing posts from January, 2011

SCTP - A new transport protocol

SCTP is a new transport protocol, also used for LTE Signalling S1-MME interface between eNB and MME (core network) and MME -HSS (Diameter / SCTP). 1 SCTP Protocol SCTP Packet is located after the MAC/ IP header. The basic SCTP Header consist of Source / Destination Ports (16 bits each), Verification Tag (32 bits) and check sum (32 bits) Verification Tag is used by the receiver to validate the senders authenticity, this get published by each endpoint to remote end duing the 4 way handshake done initially for setting up SCTP association. 1.1 4-Way handshake Msgs 1.1.1 INIT - Contains Initiate Tag, receiver window, in/out bound streams, initial TSN 1.1.2 INIT-ACK - Contains all params same as INIT msg also contains the State Cookie 1.1.3 COOKIE-ECHO - Contains Cookie same as received in INIT-ACK 1.1.4 COOKIE-ACK - Contains nothing, used to acknowledge receipt of COOKIE-ECHO Completion of above 4 SCTP msgs bring the SCTP association to an established stat