Subject: [SIP] processing late INVITEs

From: "Garret Wilson" <[email-masked]>
Date: Mon, 7 Aug 2000 16:17:24 -0700

Everyone,

What does a does a server do if an isomorphic SIP INVITE arrives after a
call completes?

For example if, through a series of forking proxies, two isomorphic INVITEs
get generated destined for a single UAS. The path that the second INVITE
takes is such that it is delayed and arrives at the UAS *after* the call
initiated by the first INVITE has finished.

Does the UAS simply ignore the second INVITE? If so, this means that the UAS
would need to keep a record of all INVITEs it has received over X amount of
time. How long would the UAS need to store this information?

Thanks in advance,

Garret Wilson

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From: Jonathan Rosenberg <[email-masked]>
Date: Tue, 08 Aug 2000 21:12:55 -0400

> What does a does a server do if an isomorphic SIP INVITE arrives after a

For proxies - nothing. Once the state of the transaction is erased, this
will look like a brand new INVITE, and be proxied merrily on its way.

As for user agent servers, the choice is yours. The INVITE state machine
itself will force you to keep state around for 32 seconds. That should
cover a pretty hefty fraction of very late packets. If you want to
extend this timer to get those 10 9's of reliability, your choice. I'm
not to worried about this problem. Worst case the phone rings again, its
picked up, 200 OK is sent, no ACK ever comes, no one talks on the other
side, and you hang up. My phone at home sometimes rings and no one is
there.

-Jonathan R.

-- 
Jonathan D. Rosenberg                       72 Eagle Rock Ave.
Chief Scientist                             First Floor
dynamicsoft                                 East Hanover, NJ 07936
[email-masked]                     FAX:   (973) 952-5050
http://www.cs.columbia.edu/~jdrosen         PHONE: (732) 741-7244
http://www.dynamicsoft.com

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From: David Shrader <[email-masked]>
Date: Thu, 10 Aug 2000 11:43:32 -0400

Jonathan, Do you actually like the fact that your phone at home rings and no
one is there? This is really annoying and will continue to grow with more
telemarketers using predictive dialing. It is not really an acceptable
side-effect of network conditions.

----------------------------
David Shrader
Master Consultant, Inc.
[email-masked]
http://www.EyeForTheFuture.com

> From: Jonathan Rosenberg <[email-masked]>
> Organization: dynamicsoft
> Date: Tue, 08 Aug 2000 21:12:55 -0400
> To: Garret Wilson <[email-masked]>
> Cc: SIP List <[email-masked]>
> Subject: Re: [SIP] processing late INVITEs
> 
> 
> 
> Garret Wilson wrote:
>> 
>> Everyone,
>>

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From: Jonathan Rosenberg <[email-masked]>
Date: Fri, 11 Aug 2000 12:37:32 -0400

Its a side effect of catastrophically bad network conditions. I expect
some conditions would be non-existent in networks used to provide
residential phone service over IP. 

-Jonathan R.