Hi Veechi,

It won't change with every transaction, just the first one after the
initial transaction. i.e.

----------------> INVITE refresher=uas
<---------------- UPDATE refresher=uac
<---------------- UPDATE refresher=uac
----------------> INVITE refresher=uas (quite possibly but not as a
result of the session timer firing)
<---------------- UPDATE refresher=uac
...

So the refresher parameter states which UA in the current transaction
will continue as the refresher. There is no consideration given to
previous transactions.

However, this behaviour is only RECOMMENDED in RFC3261 (see section 7.4
6th paragraph), either party is at liberty to switch the roles during
any INVITE/UPDATE transaction.

Cheers

Steve


-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of
[EMAIL PROTECTED]
Sent: 30 May 2008 14:59
To: [email protected]
Subject: [Sip-implementors] Refresher parameter setting rule

Hi,
Considering that both UAC and UAS support Session Timer.
If UAC sends an INVITE request with the refresher parameter set as 'uas'
in the Session-Expires header, the UAS has to have Session-Expires
header with the refresher parameter set to 'uas'.
Now when the UAS sends an UPDATE, what will the refresher parameter be
in the Session Expires header?considering the fact that the UAS of the
initial transaction is actually acting as the UAC for the current
Transaction(sending UPDATE).
Will the refresher parameter mean the 'uas' of initial transaction or
will it keep changing with every Transaction?
 
                UAC
UAS
                    |
|
                    |
|
                    |
|
 
 
Regards,
 
Veechi Jha
Project Engineer
Mobile and Consumer Electronics
Wipro Technologies
 
+91-80-28520408-7086
 

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