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

Joanne McMillen joanne at avaya.com
Tue May 20 19:42:33 EDT 2008


Bingo...  ;-)

Joanne
  ----- Original Message ----- 
  From: Elwell, John 
  To: Hiers, David ; Russell Bennett ; Zweig, Greg ; 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 

  > -----Original Message-----
  > From: techwg-bounces at sipforum.org 
  > [mailto:techwg-bounces at sipforum.org] On Behalf Of Hiers, David
  > Sent: 20 May 2008 18:28
  > To: Russell Bennett; Zweig, Greg; techwg at sipforum.org
  > Subject: Re: [SIPForum-techwg] TCP vs. UDP (SP adoption of TCP?)
  > 
  > All,
  > As a service provider using an expensive mix of best-of-breed SIP
  > implementations that service a fair number of endpoints and minutes, I
  > see the ability to use UDP as one of SIP's primary weaknesses.  
  > 
  > The attempt to supplant the TDM PSTN five-nines reliability is not
  > particularly well facilitated by running the entire show over an
  > unreliable transport protocol whose primary benefit is reduced HW
  > resource requirements.
  > 
  > When shopping for future peering partners, I would tend to prefer one
  > who's engineering philosophy happily embraces the 
  > deterministic control
  > of TCP rather than the fire-and-forget nature of UDP.
  > 
  > Best regards,
  > 
  > 
  > David Hiers
  > 
  > CCIE (R/S, V), CISSP
  > ADP Dealer Services
  > 2525 SW 1st Ave.
  > Suite 300W
  > Portland, OR 97201
  > o: 503-205-4467
  > f: 503-402-3277 
  > 
  > 
  > 
  > -----Original Message-----
  > From: techwg-bounces at sipforum.org [mailto:techwg-bounces at sipforum.org]
  > On Behalf Of Russell Bennett
  > Sent: Tuesday, May 20, 2008 9:21 AM
  > To: Zweig, Greg; techwg at sipforum.org
  > Subject: Re: [SIPForum-techwg] TCP vs. UDP (SP adoption of TCP?)
  > 
  > Greg et al.
  > 
  > I have already agreed that we have to accommodate the past, 
  > but we also
  > have to drive the future.  If we "make it OK to just offer UDP" then
  > that is what people will think that it is acceptable to do.
  > 
  > I have been actively engaged with a number of service providers for
  > quite some time now and, without naming names or providing 
  > timelines, I
  > can assure you that TCP is being deployed by service providers.
  > 
  > As for encouraging quick adoption - the issue is not one of which SIP
  > Transport is best/cheapest/already there; the issue is one of simple
  > economics: SIP Trunks cannibalize Service Provider revenues under
  > existing pricing models.  The SPs who offer "UDP only" are 
  > seeing little
  > demand for SIP Trunking - what they don't realize is that it is a
  > "chicken and egg" problem.
  > 
  > We must move SP SIP connectivity capability forward such that SPs can
  > start to deploy revenue generating services and applications 
  > to replace
  > revenue lost by decrementing PRI trunks.  We can only get to a service
  > federation model by moving rapidly beyond SIP Voice.  If we 
  > can't *even*
  > get to more broadly deployed SIP Voice, then (some) SPs will remain
  > where they are - stuck in the 20th century.
  > 
  > Forward looking SPs that I work with have heard this loud and clear.
  > 
  > UDP should be a 'MUST' to support older architectures.  TCP MUST be a
  > 'MUST' to support newer architectures.  I don't see how we accommodate
  > the past and drive the future any other way.
  > 
  > 
  > Russell
  > 
  > -----Original Message-----
  > From: techwg-bounces at sipforum.org [mailto:techwg-bounces at sipforum.org]
  > On Behalf Of Zweig, Greg
  > Sent: Monday, May 19, 2008 11:39 AM
  > To: Peter Dunkley; techwg at sipforum.org
  > Subject: Re: [SIPForum-techwg] TCP vs. UDP (SP adoption of TCP?)
  > 
  > Agreed -- We also have to consider the capabilities at the customer
  > premise.  I wouldn't want to advocate a solution that drives end
  > customers into a position where their existing equipment is made
  > obsolete.  There are many products in-use that could be upgraded to
  > other facets of a SIPconnect 1.1 implementation but will never cost
  > effectively support TCP.  I want to embrace them, not disenfranchise
  > them.
  > 
  > We need to accommodate the past while we drive the future.
  > 
  > Greg Zweig
  > Sonus Networks. Inc
  > (978) 614-8027
  > 
  > 
  > -----Original Message-----
  > From: techwg-bounces at sipforum.org [mailto:techwg-bounces at sipforum.org]
  > On Behalf Of Peter Dunkley
  > Sent: Monday, May 19, 2008 2:23 PM
  > To: techwg at sipforum.org
  > Subject: Re: [SIPForum-techwg] TCP vs. UDP (SP adoption of TCP?)
  > 
  > The danger with this approach is that you will may end up with a
  > wonderful SIPconnect 1.1 recommendation that the writers/purists love
  > but is unpalatable to the industry.
  > 
  > There needs to be a pragmatic approach taken that illustrates what SIP
  > trunking should be, while still encouraging quick adoption.
  > 
  > Making SPs have to choose between changing their architecture or
  > becomming compliant will not encourage them to adopt 
  > SIPconnect (quickly
  > 
  > or otherwise).
  > 
  > Russell Bennett wrote:
  > > All,
  > >
  > > I know from trying to work with the SPs on SIP Trunking that *some*
  > SPs are going to take a firm position on the support of UDP 
  > only.   The
  > question that Janne poses is:
  > >
  > >         1) Are we going to define SC1.1 to be what a SIP 
  > Trunk service
  > should be (e.g. UDP *and* TCP, among many other things)?
  > >         OR
  > >         2) Write SC1.1 to be what we think will enroll more 
  > SPs in the
  > SC compliance program?
  > >
  > > I argue strongly against 2 - this would not be a step forward on
  > SC1.0.  3261 is very clear on TCP support.  If SIP Forum was a
  > commercial entity, then we would go for 2 to maximize revenue.
  > >
  > > However, SF is a standards body and it is incumbent upon us 
  > to develop
  > SC1.1 as a *correct*, albeit pragmatic, document.  The key is the
  > balance between pragmatism and correctness and I, for one, think that
  > accommodating SPs that are mired in the 20th century is the wrong side
  > of that balance.
  > >
  > > Russell
  > >
  > >
  > 
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