Subject: [Sip] RFC4028 - Session Timer Clarification

From: Scott Godin <[email-masked]>
Date: Mon, 16 May 2005 11:11:06 -0400

The refresher parameter is used to indicate if the UAS or UAC is to perform
the session refreshes.

Do the terms UAS and UAC refer to the Invite Session or to the particular
transaction?

Consider the following scenario

1.	Alice Invites Bob
2.	Bob's 200 contains a refresher parameter specifying UAS (himself) as
the refresher.
3.	When Bob sends his session refresh message should it contain a
refresher parameter of UAS or UAC - assuming he wishes to continue being the
refresher?

The RFC seems to indicate he should send UAC (2nd last paragraph in section
7.4).

Thanks,

Scott

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From: Paul Kyzivat <[email-masked]>
Date: Mon, 16 May 2005 11:53:34 -0400

Scott Godin wrote:
> The refresher parameter is used to indicate if the UAS or UAC is to 
> perform the session refreshes.
> 
> Do the terms UAS and UAC refer to the Invite Session or to the 
> particular transaction?

The terminogy is indeed confusing here.

>    2. Bob's 200 contains a refresher parameter specifying UAS (himself)
>       as the refresher.
>       refresher parameter of UAS or UAC - assuming he wishes to continue
>       being the refresher?
> 
> The RFC seems to indicate he should send UAC (2^nd last paragraph in 
> section 7.4).

I agree that Bob should specify UAC to remain the refresher.

IMO the right way to think about session-timer is that every request 
that could be a session-refresh-request terminates the old session 
timer. Then it may or may not set up a new session timer. When doing so, 
the refreshed is determined relative to the current request.

	Paul