Subject: RE: [MMUSIC] ICE feature - TCP alternates for a UDP stream

From: "Francois Audet" <[email-masked]>
Date: Thu, 3 Feb 2005 17:13:41 -0500

> My first inclination was that you would still use STUN for the 
> connectivity check over TCP; irregardless of whether that tcp 
> is through 
> a TURN relay or direct (indeed, the peer in the call won't 
> normally even 
> know whether the tcp connection it will make is direct or through a 
> relay). Recall that stun can run over tcp.

Hum. If we are to use STUN on TCP, I think we need to clarify in 
draft-ietf-behave-rfc3489bis how it works. There are a number of
statements in there that sort of imply that it doesn't work with TCP.

Are you saying that you would send the binding requests on TCP?

Can you clarify what you mean by STUN over TCP?

> However, it is less useful here since establishment of the connection 
> itself could be considered a connectivity check. As such, I could go 
> either way.
> 
> Do you have a preference here, and if so, why?

I would have tought that the connection itself would be sufficient, but
maybe I'm missing some advantage that the STUN/TCP option would have. 

Anything in mind?
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From: Jonathan Rosenberg <[email-masked]>
Date: Fri, 04 Feb 2005 10:24:42 -0500

inline.

> statements in there that sort of imply that it doesn't work with TCP.

Binding allocation won't work, but you can send a request and get a 
response. Remember that the shared secret allocation messages all run 
over tcp.

> Are you saying that you would send the binding requests on TCP?

Yes, but they would do nothing more than checking liveness of the tcp 
connection.

> maybe I'm missing some advantage that the STUN/TCP option would have.

I had in mind some bizarre cases where the connection does get set up, 
but somehow the nat discards state and data can't actually get 
transmitted. Not sure this is worth worrying about.

-Jonathan R.

-- 
Jonathan D. Rosenberg, Ph.D.                   600 Lanidex Plaza
Director, Service Provider VoIP Architecture   Parsippany, NJ 07054-2711
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