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Number of transport connections among two Diameter peers

+3 votes
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I have a question on the interpretation of following paragraph from RFC 6733 section 2.1 "Transport":

A given Diameter instance of the peer state machine MUST NOT use more than one transport connection to communicate with a given peer, unless multiple instances exist on the peer, in which, case a separate connection per process is allowed.

My interpretation is that it refers to the possibility for two Diam. peers (each of them identified by its "valid" Diameter Identity - as set in section 5.1-) to establish more than one transport connections (i.e. several TCP connections or several SCTP associations -e.g. the "initiator/client" using different TCP/SCTP source ports for each of them-).

In line with this, also CER/CEA, DWR/DWA and DPR/DPA procedures must be managed per established TCP conn/SCTP assoc (as set in section 5.6) ... but (Diameter) Application specific request and answers can be sent from one peer to the other using whatever transport connection established among them (for the shared/common supported Application-Ids, of course).

Could you confirm this is the shared understanding?

A part from that, in that case, I got the following question: is it mandated that responses are sent through the same transport connection from where the (related) request-command was received?

posted Oct 17, 2013 by Kumar Mitrasen

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1 Answer

+1 vote

Whatever is written above is correct explanation. Yes it is mandated and always mandated.

Now what you are talking:
At a time with one peer we can use maximum one transport, that is the rule of client-server communication. If you have received any request with one transport it means you did handshake with say TCP so you have to reply with same transport. You don't have SCTP association with other.

If SCTP association has been developed then it means TCP connection is not there.

This is what if i think in other way: Just for knowledge
Very simple if the request is processed from TCP it means its encapsulated with TCP protocol then how SCTP can decapsulate this layer ?

Another reason is if you don't have same transports on both ends then it is not even possible to reach at application. first transport handshakes would happen then only it is possible to exchange messages in between them.

answer May 7, 2014 by Hiteshwar Thakur
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