Yeah, this is quite obscure (but I think Jiri's description is
overly complex).

I *think* that what we should say somewhere is the following:

- If this specification is supported by the registrar (as per presence of
  the Require: outbound in the 200 response to the Registration, then
  the UAC MUST do keep-alives as per section X.Y.

- In the keep-alive section, we could explain that while the keep alive
  described in this section were defined to be used by environments that
  supports this specification (Dhuh), using keep-alives in environments 
  registration as per this specification are not supported (explain how
  this is detected), is allowed if there is EXPLICIT knowledge that it is
  supported (as per the current text).

> -----Original Message-----
> From: Jiri Kuthan [mailto:[EMAIL PROTECTED] 
> Sent: Thursday, March 06, 2008 13:59
> To: Dean Willis; Dean Willis
> Cc: Audet, Francois (SC100:3055); Rohan Mahy; [email protected]
> Subject: Re: [Sip] keep-alive backwards compatibility in 
> draft-ietf-sip-outbound-12.txt
> 
> I have to admit this was too complicated for me too 
> understand. So basically UAC advertises downstream its 
> semi-transport-level keep-alive capability (CRLF/STUN) by the 
> way of app-level negotitation (reg-id), the downstream entity 
> (say a proxy-based load-balancer) signals its support for it 
> by adding PATH/ob, and the registrar UAS signals 
> load-balancer's support by Require:outbound?
> 
> So specifically if the registrar doesn't turn PATH/ob into 
> 200/Require/outbound, client shall not do ping-pong 
> keep-alive to its load-balancer?
> 
> If that's what it is, I understood the point now. 
> 
> Can someone explain to me what is the benefit of mixing 
> transport-level natping functionality with application-level 
> capabilty negotiation? My appologies if this has been 
> discussed in past years of outbound, but it is really hard to 
> understand for me. 
> 
> Thanks!
> 
> -jiri
> 
> 
> At 19:04 06/03/2008, Dean Willis wrote:
> 
> >I think we had a stale address for Jiri on this thread.
> >
> >He's been using [EMAIL PROTECTED] recently, and I'm getting no 
> DNS hit on 
> >fokus.
> >
> >
> >
> >Dean Willis wrote:
> >> 
> >> On Mar 5, 2008, at 7:00 PM, Francois Audet wrote:
> >> 
> >>> Jiri,
> >>>
> >>> On p.15 it is explained that the UAC looks at the presence of the 
> >>> Require: outbound field falue in a response to registration.
> >> 
> >>> This is to ensure that both the registrar and the edge proxy are 
> >>> compliant with this spec. The keep-alive would only be sent if 
> >>> present.
> >>>
> >> 
> >> I'm going to have to go study this, because ordinarily Require has 
> >> nothing to do with the edge proxy (which would have been 
> only looking 
> >> at Proxy-Require), and it's pretty much meaningless in responses 
> >> anyhow -- it's only processed in requests AFAIK.
> >> 
> >> I think we're trying to catch fish with a bullet again.
> >> 
> >> --
> >> Dean
> >> 
> 
> 
> 
> --
> Jiri Kuthan            http://iptel.org/~jiri/
> 
> 
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