Christian,

see inline

----- Original Message ----- 
From: "Christian Jansson" <[EMAIL PROTECTED]>
To: "Ranga" <[EMAIL PROTECTED]>; "Paul Kyzivat" <[EMAIL PROTECTED]>
Cc: <[email protected]>; "M. Rangnathan" <[EMAIL PROTECTED]>
Sent: Wednesday, March 08, 2006 10:22 AM
Subject: Re: [Sip-implementors] Difference between a BBUA and stateful proxy


>
> A lot of text has been written but no one really answered my question,
> so I will try it again.
>
>
>> Paul Kyzivat wrote:
>>
>>- a dialog stateful proxy will maintain dialog state, which consists
>>   primarily of callid, cseq, local and remote targets (contacts),
>>   and route set.
>
> What is the reason a proxy would want this information given that a
> proxy can't send requests?
>

A proxy can "send" (in the sense of initiate, not only forward) CANCEL and 
ACK for non-2xx, so technically it can send requests. A "pure" proxy would 
not initiate other requests such as BYE, but "hybrid" proxies (i.e. those 
acting as proxy but also as a special kind of UA) do.

The dialog state would be needed to construct e.g. a BYE request that 
arrives at and is accepted by one or both parties in the call (it needs to 
have the proper call-id, tags, route headers, CSeq, etc). Typically this is 
done to enforce certain policies in some network environments.

Regards,

jeroen

> Why would anyone like to build a dialog stateful proxy? In what way
> could a dialog stateful proxy use the information in the dialog that it
> has saved?
>
> / Christian Jansson
>
>
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