Subject: [Sip] draft-ietf-sip-gruu-10.txt

From: [email-masked]
Date: Fri, 4 Aug 2006 09:22:36 -0400

I read section 8 of the -10 draft to see if certain passages I'd been
having trouble understanding had been resolved, and I ran into the
following difficulties:

In 8.2.2, I see "The rules in Section 8.1.1 ensure that at least one
proxy in the same domain of the home proxy will be visited."  In the
context, it appears that this is stating that 8.1.1 ensures that a UA
in a domain that issues GRUUs will always have its UAs use an outbound
proxy.  And yet I can't see how 8.1.1 forces that, especially in light
of the statement "Note that this specification does not require the
use of an outbound proxy".

And some wording issues:

   When using a service route,
   this requirement (that the GRUU be obtained from a domain that will
   be visited by the request) it is sufficient to use the GRUU learned
   in the same registration that delivered the service route.

This doesn't parse.  Possibly it should read "... to satisfy this
requirement (...), it is sufficient ...".

   Note that this specification does not require the use of an outbound
   proxy; it merely introduces the previous requirements in cases where
   one is used.

I think that "previous" won't be read as intended, as I interpreted it
to mean "backward in time (to RFC 3261)", not "the previous paragraph
in this document".  How about "...; but in cases where one is used, it
adds the above requirements."?

   The
   rules in Section 8.1.1 ensure that at least one proxy in the same
   domain of the home proxy will be visited.

"the same domain of" s.b. "the domain of".

Also, this entire paragraph is written in reverse logical sequence.
IMHO, it's better to give causes before effects, even if that delays
stating the requirement itself:

   Firstly:  The rules in Section 8.1.1 ensure that at least one proxy
   in the same domain of the home proxy will be visited.  A home proxy
   can use mechanisms such as Service-Route [27] or UA configuration
   to ensure that it, or a proxy in the same domain, is on the
   outgoing request path.  If such a proxy receives a dialog forming
   request from a UA in its own domain (an originating request) whose
   Contact header field contains a GRUU (indicated by the presence of
   the "gruu" URI parameter) that is also in that domain, the proxy
   MUST generate a record-route which will route to the home proxy.
   
Of course, this is dependent on resolving the content issue above.

Dale

_______________________________________________
Sip mailing list  https://www1.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

---

From: Jonathan Rosenberg <[email-masked]>
Date: Tue, 08 Aug 2006 15:20:05 -0400

Thanks for the comments. More inline.

> use of an outbound proxy".

This is a bug. It should say that, if an outbound proxy is used at all, 
then the request will visit a proxy in the home domain. But, its valid 
to use gruu without any outbound proxies.

> requirement (...), it is sufficient ...".

My bad. How about:

When using a service
	      route, this requirement (that the GRUU be obtained from
	      a domain that will be visited by the request) is readily
	      met by using the GRUU learned in the same REGISTER
	      response that delivered the service route.

> adds the above requirements."?

Changed to:

	      <t>Note that this specification does not require the use
	      of an outbound proxy; the behaviors defined in the
	      previous paragraph only apply in cases where one is
	      used. </t>

> "the same domain of" s.b. "the domain of".

Fixed.

>    MUST generate a record-route which will route to the home proxy.

OK. I reworded thusly:

	      <t>
		There are two distinct requirements for record-routing
		- in the originating domain and in the terminating
		domain.
	      </t>

	      <t>
		This specification does not require that a UA use an
		outbound proxy, in which case a dialog forming request
		may not visit any proxies in the originating
		domain. However, if the UA is using an outbound proxy,
		the rules in <xref target="sec-sendto"/> require that
		at least one proxy in the domain of the home proxy be
		visited. A home proxy can use mechanisms such as
		Service-Route <xref target="RFC3608"/> or UA
		configuration to ensure that it, or a proxy in the
		same domain, is on the outgoing request path. If such
		a proxy receives a dialog forming request from a UA in
		its own domain (an originating request) whose Contact
		header field contains a GRUU (indicated by the
		presence of the "gruu" URI parameter) that is also in
		that domain, the proxy MUST generate a record-route
		which will route to the home proxy.
	      </t>

Thanks,
Jonathan R.
-- 
Jonathan D. Rosenberg, Ph.D.                   600 Lanidex Plaza
Cisco Fellow                                   Parsippany, NJ 07054-2711
Cisco Systems
[email-masked]                              FAX:   (973) 952-5050
http://www.jdrosen.net                         PHONE: (973) 952-5000
http://www.cisco.com