[cisco-voip] NAT on Cisco IOS

[Brett Looney]

At 22:12 5/08/2005, you wrote:
>I am running my Call Manager and the IP Phones behind
>the NAT. I have cisco 2621XM router with 12.3.14T2
>IPVoice IOS. Call Manager is configured with static
>NAT while IP Phones are on Dynamic NAT. H323 is used
>for call setup.
>
>Randomly, the router stops doing NAT and call manager
>cannot establish the call. Untill i have to clear
>static with 'no' command and then configure it again.
>Below is the message i get.

If you do a "show ip nat translation" when NAT stops behaving correctly do 
you see an entry with "icmperr" in the protocol column? I was having that 
problem with 12.3(14)T2 on a 2821 and 12.3(14)T3 didn't fix it. If so, you 
may find that "clear ip nat translation *" also returns NAT to an operating 
state.

I couldn't find much about the "icmperr" entry besides one very cryptic 
posting but in the end, I blocked all ICMP packets from the offending 
server and it is all good now...

HTH.

B.