Subject: [Sip] INVITE dialogs

From: Pamela Zave <[email-masked]>
Date: Tue, 14 Oct 2008 13:21:52 -0400

At the suggestion of Paul Kyzivat and Dale Worley, I compared

draft-ietf-sipping-race-examples-06.txt

to the basic Spin model of INVITE dialogs at

http://www.research.att.com/~pamela/sip.html.

Of the 13 race conditions in the sipping draft, 6 of them are out of  
the scope of the Spin model.  Most commonly, this is because they  
include retransmission of a lost message.  There are no transmission  
failures in the Spin model.

Of the remaining 7, all of them are in the Spin model, handled the  
same way.

In addition, the Spin model shows 42 additional race conditions.   
This count is subject to a lot of interpretation, so I estimate a  
possible error of about 20%.

Pamela Zave
_______________________________________________
Sip mailing list  https://www.ietf.org/mailman/listinfo/sip
This list is for NEW development of the core SIP Protocol
Use [email-masked] for questions on current sip
Use [email-masked] for new developments on the application of sip

---

From: Pamela Zave <[email-masked]>
Date: Fri, 24 Oct 2008 15:27:18 -0400

The count of new races is rather arbitrary, of course, but some are  
serious ones requiring significant programming effort to work  
around.  As Paul says, removing my simplifying assumptions can only  
make the problem worse, not better.

I realize that it is not easy for someone new to delve into the model  
quickly.  I propose to extract a few cases that I find interesting,  
check them with experts for validity to avoid wasting everyone's  
time,  and post a readable summary.  Then everyone should be able to  
assess the substance.

I am about to leave for a week of vacation, so ETA is the first week  
of November.

I hope this is helpful.
Cheers,
Pamela

On Oct 24, 2008, at 1:32 PM, Paul Kyzivat wrote:

> Pamela,
>
> Will you perchance be attending IETF73 in Minneapolis this Nov?
>
> There is some interest in having you talk about the race conditions  
> you say you have found.
>
> 	Thanks,
> 	Paul
>
> Pamela Zave wrote:
>> Of the 13 race conditions in the sipping draft, 6 of them are out  
>> of the scope of the Spin model.  Most commonly, this is because  
>> they include retransmission of a lost message.  There are no  
>> transmission failures in the Spin model.
>> Sipping mailing list  https://www.ietf.org/mailman/listinfo/sipping
>> This list is for NEW development of the application of SIP
>> Use [email-masked] for new developments of core SIP

---

From: Paul Kyzivat <[email-masked]>
Date: Fri, 24 Oct 2008 16:25:43 -0400

Pamela Zave wrote:
> serious ones requiring significant programming effort to work around.  
> As Paul says, removing my simplifying assumptions can only make the 
> problem worse, not better.
> 
> check them with experts for validity to avoid wasting everyone's time,  
> and post a readable summary.  Then everyone should be able to assess the 
> substance.

I like that idea a lot!

	Thanks,
	Paul

> I am about to leave for a week of vacation, so ETA is the first week of 
> November.
> 
> I hope this is helpful.
> Cheers,
> Pamela
> 
>