Subject: [Sip] Keep draft and manipulation of Via header on-stack

From: Dean Willis <[email-masked]>
Date: Mon, 12 May 2008 12:22:15 -0500

draft-holmberg-sip-keep-00 section 7 says:
When an edge proxy that supports the method defined in this  
specification recieves a SIP REGISTER request which contains a "keep"  
parameter in the topmost Via header the edge proxy MUST add a "yes"  
value to the "keep" parameter. In addition the edge proxy MAY include  
a Flow-Timer header field if the associated SIP REGISTER response.
I think this is the first time I've seen a specification that causes a  
proxy to modify a Via that was already in the request.
So we really want to do this, or do we want the proxy to be adding its  
own Via with "keep=yes"?

--
Dean
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---

From: "Brett Tate" <[email-masked]>
Date: Mon, 12 May 2008 13:49:24 -0400

> I think this is the first time I've seen a 
> specification that causes a proxy to modify 
> a Via that was already in the request.

RFC 3581 performs a similar modification concerning rport.

> So we really want to do this, or do we want 
> the proxy to be adding its own Via with "keep=yes"?

The draft's proposed mechanism allows support and desired use to be
clearly indicated by both sender and receiver at a hop level.  Such a
concept outbound/keepalive stuff was briefly discussed back in 2006:
http://www.ietf.org/mail-archive/web/sip/current/msg13733.html

---

From: Bob Penfield <[email-masked]>
Date: Mon, 12 May 2008 14:00:22 -0400

Modifying the Via is not without precedent.

  RFC 3261 requires the "received=" parameter be added.

And modifying the value of a parameter in the Via is also  not without precedent.

  RFC 3581 defines this behavior for the "rport" parameter.

   When a server compliant to this specification (which can be a proxy
   or UAS) receives a request, it examines the topmost Via header field
   value.  If this Via header field value contains an "rport" parameter
   with no value, it MUST set the value of the parameter to the source
   port of the request.  This is analogous to the way in which a server
   will insert the "received" parameter into the topmost Via header
   field value.

cheers,
(-:bob

---

From: "Bharrat, Shaun" <[email-masked]>
Date: Mon, 12 May 2008 21:49:24 -0400

> So we really want to do this, or do we want the proxy to be adding its  

Aside from the received= counter example, I'm not sure that adding the keep=yes
to the proxy's via would even work. Isn't the keep=yes also used by the *client*
to know that STUN is allowed on the SIP port? If the keep=yes is only on
the proxy's via, that is not there in the response finally seen by the client.

Cheers,
Shaun

---

From: "Christer Holmberg" <[email-masked]>
Date: Tue, 13 May 2008 07:16:33 +0200

Correct. keep=yes must be in the client Via, in order for the client to
receive it.

Regards,

Christer 

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf Of
Bharrat, Shaun
Sent: 13. toukokuuta 2008 4:49
To: Dean Willis; [email-masked]
Subject: Re: [Sip] Keep draft and manipulation of Via header on-stack

> own Via with "keep=yes"?

Aside from the received= counter example, I'm not sure that adding the
keep=yes to the proxy's via would even work. Isn't the keep=yes also
used by the *client* to know that STUN is allowed on the SIP port? If
the keep=yes is only on the proxy's via, that is not there in the
response finally seen by the client.

Cheers,
Shaun

_______________________________________________
Sip mailing list  https://www.ietf.org/mailman/listinfo/sip
This list is for NEW development of the core SIP Protocol Use
[email-masked] for questions on current sip Use
[email-masked] for new developments on the application of sip

_______________________________________________
Sip mailing list  https://www.ietf.org/mailman/listinfo/sip
This list is for NEW development of the core SIP Protocol Use
[email-masked] for questions on current sip Use
[email-masked] for new developments on the application of sip
_______________________________________________
Sip mailing list  https://www.ietf.org/mailman/listinfo/sip
This list is for NEW development of the core SIP Protocol
Use [email-masked] for questions on current sip
Use [email-masked] for new developments on the application of sip