Subject: [Simple] COMEDIA vs MSRP Relays: Which Connection?

From: Ben Campbell <[email-masked]>
Date: Mon, 20 Jul 2009 16:12:32 -0500

(As individual)

We've had quite a bit of discussion about how the Transport Connection  
Addressing Section (draft-ietf-simple-msrp-acm-00 section 4.2) may or  
may not work with MSRP relays. I'd like to make sure we're not  
neglecting how the COMEDIA Usage section (Section 4.1 and children)  
interact with MSRP relays.

I think there are some open questions. Since each one seems likely to  
generate a thread of discussion, I'm sending them separately:

When MSRP relays are present, there will be two or more TCP  
connections involved in a particular session. Which connection is  
being negotiated via COMEDIA?

I _think_ the answer is the connection between boundary relays--that  
is, between the outermost relay of party A and the outermost relay of  
party B. If one party uses a chain of relays, only the outer one would  
require COMEDIA negotiation. I guess you could also look at this as  
the connection that crosses domains, for some vague definition of  
domain.

There might be an interesting case here for when both parties share  
the same relay.

---

From: Hadriel Kaplan <[email-masked]>
Date: Tue, 21 Jul 2009 18:10:23 -0400

I assumed the same: that it's the connection to/from the (last) relay from each side's perspective, facing to the public internet.  As if the Relay were a TURN server, I guess.  In other words, what would have been the first MSRP URI in the use-path list in SDP.

-hadriel

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From: "Christer Holmberg" <[email-masked]>
Date: Wed, 22 Jul 2009 01:06:32 +0200

Hi,
 
This is listed as an open issue in my presentation.
 
It is related to an issue raised by Ben a while ago, that comedia also decides which party sends the first MSRP message. 
 
So, combining the solution proposals for both issues: if a client behind a relay is "passive", it would still establish an TCP connection with its relay, but it would not send the first MSRP SEND. 
 
Regards,
 
Christer

________________________________

From: [email-masked] on behalf of Hadriel Kaplan
Sent: Wed 22/07/2009 00:10
To: Ben Campbell; Simple WG
Subject: Re: [Simple] COMEDIA vs MSRP Relays: Which Connection?

-hadriel