Why LTE uses GTP-C signaling between MME to SGW or SGW to PGW instead of SCTP?

Question

I recently come across advantages of SCTP over TCP and In telecommunication most of the real time interfaces require SCTP connection example eNB to MME.

But MME to SGW and SGW to PGW GTP-C is used as signaling protocol. Why SCTP not being used? What is the advantage of using GTP-C?

Answer 1

GTP stands for "General Packet Radio Service Tunneling Protocol". This protocol supports tunneling concepts that are used for IP packets flow from UE to external world and vice a versa. There is no need of connection oriented protocol for flow of IP packets, therefore UDP is used at transport level. Some application/protocol is required to support and differentiate millions of sessions, that application protocol is known as GTP protocol.

GTP deals with control as well as data plane, that is the reason of having two variants i.e. GTP-C and GTP-U.
Since UDP is a connection less protocol, GTP provides echo request/response messages to check the availability of peer.

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