On Fri, 2009-06-19 at 13:41 -0400, Robert Joly wrote:
> Folks,
> Whenever a remote worker registers with wipXecs, the sipXproxy process
> will start maintaining the pinhole to the remote worker by sending an
> OPTIONS message every 20 seconds.  This process ensures that the
> firewall & NAT in front of the remote worker will accept and forward
> incoming requests from sipXecs.  Without that process, the firewall
> would close the pinhole some time after the phone's last transmission. 
> 
> Recently, we have experienced some problems in the lab whereby
> restarting the sipXproxy process can interrupt the generation of
> pinhole-maintaining OPTIONS messages for up to 3 minutes.  This
> interruption is enough for many firewalls to close their pinholes
> rendering the phones behind them unreachable from the POV of sipXecs.
> This situation heals itself the next time the remote phone refreshes its
> registration but because sipXecs's max expiry value is one hour, a
> remote phone can lose its ability to receive incoming for a full hour
> following a sipXproxy restart.
> 
> To solve this situation, I can see two approaches which are not mutually
> exclusive:
> 
> 1- for remote phones that support a SIP keepalive feature, that feature
> should be turned on;

Obviously a good idea, assuming that what the phones do is itself
reasonable (hopefully they just send a CRLF every so often - that being
much cheaper than a SIP request).

> 2- sipXecs should significantly reduce the maximum registration expiry
> for remote phones to something like 5 minutes.  

How would you propose that the registry recognize that a phone needs
this shortened registration period?

> The latter would increase the work load of sipXecs but would ensure that
> every phone returns to a fully functional state within 5 minutes of a
> system reboot, sipXproxy reboot or network outage.  I'm not too
> concerned about the increased work load - here is why.  Earlier this
> year I was doing performance measurements on sipXecs and as part of my
> test setup, I had to register 5400 users very often.  I had a SIPP
> script that was doing the bulk registration at a rate of 100reg/sec and
> the system could very easily cope with such a load...  

Was that an HA system?  

Isn't there a third case - for phones using UDP at least, the proxy
could persist the keepalive targets so that it could start sending to
them after a restart.



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