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Re: [Msrp] Connection Sharing in MSRP



On Feb 6, 2006, at 9:07 AM, Sudha wrote:

Hi All,

With Reference to draft-ietf-simple-message-sessions-2.txt

First, you are looking at a very old draft--the current one is draft- ietf-simple-message-sessions-13. A version 14 will be coming out shortly, but I do not expect it to contain any substantive changes.


"When an MSRP endpoint wishes to send a request to a peer identified by an MSRP URL, it first needs a transport connection, with the appropriate security properties, to the host specified in the URL. If the sender already has such a connection, that is, one associated with the same host, port, and URL scheme, then it SHOULD reuse that connection."

In this case,

If the Source Port, Target Port, Source IP, Traget IP and security scehme of a particular connection matches it can be reused.

Hence same connection can be used by 2 or more sessions each of them having differnt Session IDs.

My doubt here is when does such a scenario arise? The msrp URLs are given by SDP. The SDP doesnt reuse the same port in the MSRP URL when it is already in Use.

Can you please help me on understanding the scenario when MSRP
Connection sharing may occur.

The SDP certainly can reuse the same MSRP port if an implementation chooses to do so. But the real use of this is for when relays are involved. You could have any number of MSRP sessions with multiple peers going across the same outbound relay. In this case, you should not create a separate TCP connection to that relay for each of the sessions. This is even more true for connections between an adjacent pair of relays that may carry any number of active sessions.

Hope this helps.

Ben.