[Serusers] Question about general SIP timers in productionenviroments.

Jiri Kuthan jiri at iptel.org
Mon Dec 27 10:13:42 CET 2004


At 08:48 AM 12/24/2004, Greger V. Teigre wrote:
>This is dependent on the type of deployment and your preferences.  If you have a deployment scenario with fixed line replacement, you probably have users who don't move around a lot.  Then 3,600 seconds is a typical number.

We typically set lower than that -- NATs, rebooted devices and other surprise 
cause sometimes for invalid bindings and 10 minutes seems a reasonable compromise
between robustness of bindings and too heavy traffic. There is no computational
justification though -- it is just a value we "decided" some day back ago to be 
ok :)

>   Sending NOTIFY as a way to keep the NAT open is something you should avoid. I don't know who started this, but sending an empty UDP is more than enough and does not require ser to do any processing of the incoming packet. Of course, if NOTIFY is used for communicating something, it's a different thing...
>   The minimum ping time configurable in UAs is often 20 seconds. Normally, you could ping every minute or so and everything would be fine. The problem is that you will not know which UAs that are behind NATs with low expiry time. Also, if the NAT mapping table starts getting full, the expiry time will often be reduced.

I would tend to leave it at 20 seconds. I think some *BSD NATs have sub-1-minute timing
expiration time.

-jiri 




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