Subject: [Sip] Fwd: I-D Action:draft-lendl-enum-sip-lr-00.txt

From: Otmar Lendl <[email-masked]>
Date: Mon, 5 May 2008 16:43:36 +0200

fyi,

I've taken up the bait contained in Section 6 (last paragraph) of
draft-rosenberg-sip-ua-loose-route-02, and published a quick draft
describing how this idea could be implemented in an ENUM setting.

Comments are welcome.

/ol

----- Forwarded message from [email-masked] -----

A New Internet-Draft is available from the on-line Internet-Drafts directories.

	Title           : IANA Registration for the enumservice-subtype 'sip:lr'
	Author(s)       : O. Lendl
	Filename        : draft-lendl-enum-sip-lr-00.txt
	Pages           : 7
	Date            : 2008-05-02

This document requests IANA registration of an enumservice-subtype
for loose route variant for SIP, the Session Initiation Protocol.
This subtype allows for the routing of SIP messages addressed to tel:
Uniform Resource Identifiers (URIs) according to
[I-D.rosenberg-sip-ua-loose-route].

A URL for this Internet-Draft is:
http://www.ietf.org/internet-drafts/draft-lendl-enum-sip-lr-00.txt

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From: Hans Erik van Elburg <[email-masked]>
Date: Tue, 6 May 2008 00:53:04 -0700 (PDT)

Hi Otmar,

Interesting, but this has nothing to do with "UA loose-routing". Everything
with the retarget or reroute problem. 

It seems an interesting way of configuring loose routes, but it also still
requires configuration of normal DNS entries as the resolver may not support
this sip:lr NAPTR application.

The requirement to know if the next hop supports this yes or no, seems to be
less of an issue as the configurator of the DNS should be expected to be
able know this at configuration time.

This mechanism can be combined with the Target header proposal. 

/Hans Erik 

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From: Otmar Lendl <[email-masked]>
Date: Tue, 6 May 2008 13:13:31 +0200

Hi,

> with the retarget or reroute problem. 

I took the "UA loose route" from the name of Jonathan's draft.

> this sip:lr NAPTR application.

Yes, for backwards compatibility normal E2U+SIP NAPTRs might be
provisioned, too.  I expect this to be used mainly in controlled
environements like private SIP peering platforms (Infrastructure ENUM
or private ENUM) where one has a cleared picture on who will query such
records.

> able know this at configuration time.

Correct, according to the original ENUM role model, the destination network
provisiones the ENUM NAPTRs pointing to its ingress elements.

> This mechanism can be combined with the Target header proposal. 

Could you give an example? I have difficulties imaging the message flows
and routing logic when doing tel:-URI based calling. This paragraph is
unclear:

   The Target header, if present, represents the current target.  In the
   absence of the Target header, a receiving entity must assume that the
   Request-URI contains the current target.  Note that the Target header
   is not used for routing, it is just a means of presenting the current
   target to the receiving entity, information that otherwise would have
   been lost.

So which is it? Does the receiving entity evaluate the target: header or
the request-URI?

/ol

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From: Hans Erik van Elburg <[email-masked]>
Date: Tue, 6 May 2008 04:48:20 -0700 (PDT)

As stated the Target header field is not used for routing. If all the hops
are loose routes it is still able to carry the current target over the last
hop to the UE, where the Request URI is rewritten by teh Contact
information.

It  is not clear to me how this would be affected by use of tel uri's. Can
you explain why you think there is a problem?

Regarding the terminating entity that may choose to not do anything with
either the Request-URI or the Target header. Even if it support the
extension it may still not use it.

/Hans Erik

Otmar Lendl-2 wrote:
> 
> 
> Hi,
> 
> On 2008/05/06 09:05, Hans Erik van Elburg
> <[email-masked]> wrote:
>> 

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