[SR-Users] [sr-dev] Testing SIP Outbound / RFC5626 (Was: Freezing for next major release)

[Peter Dunkley]

Hi Juha,

A few months ago there was a discussion on IRC and the sr-dev list about
what is needed for outbound.  This requirement to remove broken contacts
was presented then by someone as something that (although not explicit
in the RFC) is needed.

If a flow is broken, particularly one over TCP where the connection is
established from the UAC to the edge proxy, then it will never work
again.  As such it is extremely wasteful to continue to try and use that
flow (in preference to one that will work) for each new dialog forming
request.  Further, as re-REGISTER times can be quite long, not removing
broken contacts could lead to a significant/growing number of dead
contacts (all of which will be tried for each new dialog forming
request) in the location table.

There is an unregister() function in the registrar module, there are
also the reg_(fetch|free)_contacts() functions in the registrar module.
None of these appear to do quite what is required.

Peter


On Tue, 2013-01-08 at 04:46 +0200, Juha Heinanen wrote:

> Peter Dunkley writes:
> 
> > One requirement of an outbound capable registrar is that if a flow fails
> > (edge proxy returns a 430) the registrar should realise that the flow is
> > now dead and remove that contact binding from its database so it is not
> > used again as well as trying the next contact.  I can't see anything that
> > will do this?  Is this missing?
> 
> peter,
> 
> i didn't find in rfc5626 a requirement that registrar should remove 430
> flow contact, but, if there is such a requirement, in my opinion removal
> should be done from failure route in the script by a function that
> removes the contact.
> 
> a similar thing was discussed a while back (see below).
> 
> -- juha
> 
> From: Juha Heinanen <jh at tutpro.com>
> Sender: sr-dev-bounces at lists.sip-router.org
> To: sr-dev at lists.sip-router.org
> Subject: [sr-dev] git:master: usrloc(k): keep time of the last keepalive for
> 	natted UDP contacts
> Date: Thu, 13 Sep 2012 17:08:51 +0300
> 
> Klaus wrote:
> 
>    Why only UDP? Are TCP contacts removed when the TCP connections is closed?
> 
>    IMO there should also be a mechanism to remove ALL expired unresponsive 
>    contacts.
> 
> how about the following for tcp contacts:
> 
> - set_forward_no_connect();
> - if t_relay() fails because tcp connection does not exist,
>   unregister the AoR/contact
> 
> what would be needed is a find out that t_relay() failed due to
> non-existing connection and a script function to do un-registration of
> an AoR/contact.
> 
> perhaps both of these two things already exist?
> 
> -- juha
> 
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-- 
Peter Dunkley
Technical Director
Crocodile RCS Ltd
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