[SIPForum-techwg] TCP vs. UDP (SP adoption of TCP?)

[Dutkiewicz, Marek]

I will echo a response from somewhere further down this thread that
there are many service providers running VoIP services today that do not
have TCP support. We (Polycom) recently needed to add support for a
feature that generates very large SIP packets using UDP despite pointing
out that RFC3261 has a MUST relating to using TCP if there is any chance
of packet fragmentation.

 

I believe the use of UDP is often due to a nervousness of the unknowns
of upgrading to a new transport protocol. However there are probably
also network elements deployed that do not support TCP (yet).

 

I feel encouraged by the apparently strong endorsement from this group
to mandating TCP for SIPConnect 1.1, but do caution the group against
assuming this will be universal. It is likely that the 'UDP users' will
not be as vocal in a forum like this as those that are already using
TCP.

 

We should figure out a method by which SIPConnect 1.1 can require TCP
without breaking compatibility with legacy devices. Maybe it's as simple
as saying you can't get SIPConnect1.1 without supporting TCP, but a
SIPConnect1.1 device has to support UDP as a fall-back.

 

Marek

 

 

 

________________________________

From: techwg-bounces at sipforum.org [mailto:techwg-bounces at sipforum.org]
On Behalf Of Francois Audet
Sent: Tuesday, May 20, 2008 4:52 PM
To: Joanne McMillen; Elwell, John; Hiers, David; Russell Bennett; Zweig,
Greg; techwg at sipforum.org
Subject: Re: [SIPForum-techwg] TCP vs. UDP (SP adoption of TCP?)

 

So, by now, most significant PBX & UC vendors on this list seemed to
have expressed support for the idea of making TCP either mandatory or at
least the recommended option.

 

I wonder just where the UDP perceived requirement comes from. I do not
think the "well, last time I try it, there was a lot of it" argument
holds water. And the idea of a race to the bottom (i.e., UDP) sounds
self-defeating to me.

 

 

 

	 

	
________________________________


	From: techwg-bounces at sipforum.org
[mailto:techwg-bounces at sipforum.org] On Behalf Of Joanne McMillen
	Sent: Tuesday, May 20, 2008 16:43
	To: Elwell, John; Hiers, David; Russell Bennett; Zweig, Greg;
techwg at sipforum.org
	Subject: Re: [SIPForum-techwg] TCP vs. UDP (SP adoption of TCP?)

	Bingo...  ;-)

	 

	Joanne

		----- Original Message ----- 

		From: Elwell, John <mailto:john.elwell at siemens.com>  

		To: Hiers, David <mailto:David_Hiers at adp.com>  ; Russell
Bennett <mailto:Russell.Bennett at microsoft.com>  ; Zweig, Greg
<mailto:gzweig at sonusnet.com>  ; techwg at sipforum.org 

		Sent: Tuesday, May 20, 2008 12:14 PM

		Subject: Re: [SIPForum-techwg] TCP vs. UDP (SP adoption
of TCP?)

		 

		Yes, this has always been the thing that puzzled me. A
lot of vendors
		and service providers have tried to reproduce PSTN
capabilities with
		SIP. Yet PSTN signalling protocols always ran over a
reliable transport,
		so the obsession with UDP seems to be a contradiction.
		
		John 

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