Subject: RE: [Sip] How to indicate during proxy discoverythataproxysupports "outbound"

From: "Christer Holmberg" <[email-masked]>
Date: Mon, 3 Apr 2006 08:33:10 +0300

Hi Hadriel,

My mail was rabout the OPTIONS alternative. And, you wouldn't even need Require there, because the outbound proxy would simply reply what it supports. In fact, no standardization is required for that, so should we mention it as an option?

And, if there are no issues (removal of options tags from the P-R/Require header by proxy) with the REGISTER alternative I don't have any issues with that solution - as long as we document the assumptions and restriction.

Regards,

Christer
Regards,

Christr

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---

From: "Hadriel Kaplan" <[email-masked]>
Date: Mon, 3 Apr 2006 02:17:13 -0400

Funny - those were similar words to what I asked someone I know about the
Options idea a couple days ago.  The act of checking, and how, still needs
to be documented because it's simply not obvious to people.  I've been told
the support of Options, however, is unfortunately not as prevalent as one
would hope on legacy proxies. (also because it was not obvious)  Maybe the
SIPit folks have more data on that.  It's also not clear all registrars
would accept an Options before registration.

The proxy-require/require in a Register, on the other hand, works with any
proxy/registrar we've seen and is the least burden for all nodes I think.

-hadriel

> -----Original Message-----
> From: Christer Holmberg [mailto:[email-masked]]
> Sent: Monday, April 03, 2006 1:33 AM
> To: Hadriel Kaplan; [email-masked]
> Subject: RE: [Sip] How to indicate during proxy
> discoverythataproxysupports "outbound"
> 
> Hi Hadriel,
> 
> My mail was rabout the OPTIONS alternative. And, you wouldn't even need
> Require there, because the outbound proxy would simply reply what it
> supports. In fact, no standardization is required for that, so should we
> mention it as an option?
> 
> And, if there are no issues (removal of options tags from the P-R/Require
> header by proxy) with the REGISTER alternative I don't have any issues
> with that solution - as long as we document the assumptions and
> restriction.
>

---

From: "Jeroen van Bemmel" <[email-masked]>
Date: Mon, 3 Apr 2006 08:29:14 +0200

Christer,

Besides detection for support, Proxy-Require is also useful for backwards 
compatibility

Consider how the edge proxy decides whether or not it needs to perform 
outbound processing. Without Proxy-Require, it would have to either look for 
'Require: outbound' or inspect the Contact headers, look for 'reg-id' and 
assume that means the UAC supports / wants to use outbound. From a protocol 
purist perspective, both of these alternatives are less preferred than 
Proxy-Require

BTW, section 3.4 should have some text discussing this. It currently says 
"edge proxy should use Path" but the processing seems to depend on the fact 
that there is a 'reg-id'. What if there is none?

Regards,

Jeroen

----- Original Message ----- 
From: "Christer Holmberg" <[email-masked]>
To: "Hadriel Kaplan" <[email-masked]>; <[email-masked]>
Sent: Monday, April 03, 2006 7:33 AM
Subject: RE: [Sip] How to indicate during proxy 
discoverythataproxysupports"outbound"

Hi Hadriel,

And, if there are no issues (removal of options tags from the P-R/Require 
header by proxy) with the REGISTER alternative I don't have any issues with 
that solution - as long as we document the assumptions and restriction.

Regards,

Christer
Regards,

Christr