Re: [Sipping] Liaison Statement on offer/answer procedures

["Christer Holmberg" <[e-mail]>]

Hi,
 
I do NOT think John's case is connected to the rollback issue.
 
The rollback issue is: what happens to data that has been updated between the re-INVITE request and failure response? It of course included the target, but is not related to where responses are sent.
 
Responses are, afaik, always sent to where the request came from, so if one updates the local target he has to make sure that he listens to the "old" port if there are ongoing transactions.
 
Regards,
 
Christer
 
 

________________________________

Lähettäjä: Paul Kyzivat [mailto:[e-mail]]
Lähetetty: pe 16.5.2008 14:38
Vastaanottaja: Elwell, John
Kopio: Christer Holmberg; sipping List
Aihe: Re: [Sipping] Liaison Statement on offer/answer procedures



John,

This is a good point.

It does expose a potentially long window when address changes are
problematic. I guess if a quick address change is necessary then the
INVITE, or reINVITE, can be CANCELed.

IMO this is starting to identify an area that could stand to have more
specification. I guess this sounds like a best practices draft, but its
still a little fuzzy to me. And I am far from clear whether this is
tightly connected to the o/a rollback issue.

        Thanks,
        Paul

Elwell, John wrote:
> Paul,
>
>
>> -----Original Message-----
>> From: [e-mail]
>> [mailto:[e-mail]] On Behalf Of Paul Kyzivat
>> Sent: 15 May 2008 14:48
>> To: Christer Holmberg
>> Cc: sipping List
>> Subject: Re: [Sipping] Liaison Statement on offer/answer procedures
>>
>> Christer,
>>
>> Saying "you shouldn't do it" to changing contact address or media
>> address ignores facts of life that may require doing it. This
>> overlaps
>> strongly with the session mobility discussion that is
>> currently going on.
>>
>> Specifically, if a UA is losing possession of its address, or
>> connectivity via that address, then it will have to do
>> *something*. If
>> we are going to say that you shouldn't change the contact
>> address in a
>> dialog, and shouldn't change the media address in a media
>> session, then
>> we need to specify some alternative.
>>
>> Clearly there are at least two distinct cases here:
>>
>> - there is a desire to switch to a new address, but the old address
>>    can continue to be supported until and unless use of the new one
>>    can be established
> [JRE] So if the contact address changes and we successfully conclude the
> UPDATE transaction, and then the old contact address disappears, it is
> likely that the Via list on the re-INVITE request will have become
> invalidated too, so the final response will not reach the UAC. Correct?
>
> John
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