[Asterisk-Users] Cisco IOS crash with multiple SIP endpoints behind NAT

David Croft davidc at sargasso.net
Thu Mar 18 18:29:27 MST 2004

Thought I'd drop a note here in case anyone else has been experiencing 
this. Cisco routers running NAT are liable to crash when doing NAT 
translation of SIP packets. Symptoms are a watchdog caused software 
abort in the "IP Input" process. The router then reloads. In my case 
this has been happening every ~24 hours with one SIP device behind the 
NAT and every ~15 minutes with three devices.

Cisco have identified this as bug ID CSCed42990 
but it is not yet fixed in a released version. You can get an interim 
release from TAC if you have a service contract.

According to the bug description this only affects 12.3, but it 
definitely happened in the 12.2T train too (this is why we upgraded to 


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