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 PROTECTED]> wrote:
>> 
>> Interesting, but this has nothing to do with "UA loose-routing".
>> Everything
>> with the retarget or reroute problem. 
> 
> I took the "UA loose route" from the name of Jonathan's draft.
> 
>> 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.
> 
> 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.
> 
>> 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.
> 
> 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
> -- 
> -=-  Otmar Lendl  --  [EMAIL PROTECTED]  -=-
> _______________________________________________
> Sip mailing list  https://www.ietf.org/mailman/listinfo/sip
> This list is for NEW development of the core SIP Protocol
> Use [EMAIL PROTECTED] for questions on current sip
> Use [EMAIL PROTECTED] for new developments on the application of sip
> 
> 

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