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@tutpro.com>
Sender: sr-dev-bounces@lists.sip-router.org
To: sr-dev@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