Subject: [Sip] Open Issue #210: T1 at client needed to tune T3 at server

From: Jonathan Rosenberg <[email-masked]>
Date: Thu, 6 Dec 2001 15:07:34 -0500

Issue:

Minor issue.

In the invite client transaction machine, it remains in the completed state
for T3. The completed state is the state where the client has received the
final non-2xx response, and has sent the ACK. It now waits for subsequent
retransmits of the final response in order to resend the ACK. It waits in
this state until Timer D fires. Timer D represents the total amount of time
that the server could conceivably retransmit the final non-2xx response.
That amount of time is defined, for unreliable transports, by Timer H, which
is the amount of time the server transaction spends in the completed state
before giving up. The spec says that this is T3, but its actually 64*T1
(that is an error in the spec). In either case, the timeout at the client
depends on the value of T1 selected by the server. But it doesn't know this
value. What do we do?

Discussion:

Communicating T1 is too complex. Let us simply choose a minimum value for
Timer D in the case of unreliable transports. The obvious value is the
default value of 64*T1, which is 32s.

I believe there are a few other places in the spec where there is a
dependency on knowing T1 on the other side. We would need a similar change
there.

Proposal:

Define Timer D as having a minimum value of 32s for unreliable transports.
Apply same process for any other timers.

-Jonathan R.
---
Jonathan D. Rosenberg, Ph.D.                72 Eagle Rock Ave.
Chief Scientist                             First Floor
dynamicsoft                                 East Hanover, NJ 07936
[email-masked]                     FAX:   (973) 952-5050
http://www.jdrosen.net                      PHONE: (973) 952-5000
http://www.dynamicsoft.com

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---

From: Jonathan Rosenberg <[email-masked]>
Date: Thu, 27 Dec 2001 02:38:43 -0500

There were no comments on this proposal. I will interpret silence as 
acceptance of the proposal. Issue resolved.

-Jonathan R.

-- 
Jonathan D. Rosenberg, Ph.D.            72 Eagle Rock Avenue
Chief Scientist                         First Floor
dynamicsoft                             East Hanover, NJ 07936
[email-masked]                 FAX: (973) 952-5050
http://www.jdrosen.net                  PH:  (973) 952-5000
http://www.dynamicsoft.com