Subject: [Sip] Changes to the INVITE transaction to address bug 769

From: Robert Sparks <[email-masked]>
Date: Wed, 27 Jun 2007 19:35:14 -0700

Everyone -

I've put together a proposal for addressing the spec bug captured at
http://bugs.sipit.net/show_bug.cgi?id=769

Please read through
http://www.ietf.org/internet-drafts/draft-sparks-sip-invfix-00.txt
and comment.

RjS

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---

From: Paul Kyzivat <[email-masked]>
Date: Thu, 28 Jun 2007 08:56:43 -0400

Robert,

I seem to recall from long ago that one reason for forwarding strays was 
to support restart or failover of a proxy, where internal state of the 
failed proxy is not preserved. As I recall, the expectation was that 
while things might not work as well as if the failure had not happened, 
the situation would be better than if these messages were not forwarded.

This is only a vague memory, so it may not be right. But if it is, won't 
the proposed changes break that? Does it matter?

Also, while I see some logic in not forwarding strays for the reasons 
stated in the draft, if that is a problem that needs to be solved, 
shouldn't stateless proxies also be banned?

	Paul

---

From: "Gilad Shaham" <[email-masked]>
Date: Thu, 28 Jun 2007 15:27:41 +0100

I guess a stateful proxy would only need stateless forwarding only in
the first few minutes of operation (because of timer C) - after that it
should have all the transactions. Not sure we can or want to ban
stateless proxies though. Isn't this "recovery mode" simply the same as
saying that for the first few minutes the stateful proxy acts as both
stateful and stateless proxy?

> -----Original Message-----
> From: Paul Kyzivat [mailto:[email-masked]]
> Sent: Thursday, June 28, 2007 3:57 PM
> To: Robert Sparks
> Cc: SIP IETF
> Subject: Re: [Sip] Changes to the INVITE transaction to address bug
769

---

From: Robert Sparks <[email-masked]>
Date: Thu, 28 Jun 2007 18:13:46 -0700

Yeah - stateless proxies have a similar admission policy problem for  
responses as they are
defined in 3261. You can address that (I think) without requiring  
them to keep transaction state
though (I think). It would involve something along the lines of  
providing bits to themselves that
they see in the response that lets them know this response  
corresponds to a request they actually
forwarded recently (it would require them to have a clock to  
reference, but they wouldn't have to
keep timers).

RjS

On Jun 28, 2007, at 5:56 AM, Paul Kyzivat wrote:

> Robert,
>
> I seem to recall from long ago that one reason for forwarding  
> strays was to support restart or failover of a proxy, where  
> internal state of the failed proxy is not preserved. As I recall,  
> the expectation was that while things might not work as well as if  
> the failure had not happened, the situation would be better than if  
> these messages were not forwarded.
>
> This is only a vague memory, so it may not be right. But if it is,  
> won't the proposed changes break that? Does it matter?
>
> Also, while I see some logic in not forwarding strays for the  
> reasons stated in the draft, if that is a problem that needs to be  
> solved, shouldn't stateless proxies also be banned?
>
> 	Paul
>
> Robert Sparks wrote:
>> Everyone -