High CPU Due to NAT

witani · ‎11-25-2010

Dears,

I have a 7206 VXR NPE-G2 running in an ISP at 40% CPU in peak time.

I applied NAT with overload based on the ACL below. After that, CPU started to reached 90 % in peak time.

Is that expected or I am missing something ?

Extended IP access list MATCH_VOIP

30 permit udp any any eq 5070

35 permit tcp any any eq 5070

40 permit udp any any eq 5060

45 permit tcp any any eq 5060

50 permit udp any any eq 1720

55 permit tcp any any eq 1720

60 permit udp any any eq 1731

65 permit tcp any any eq 1731

ip nat inside source route-map NAT_VOIP_GLOBAL pool VOIP_GLOBAL overload

Regards,

Marc Faggion · ‎11-28-2010

The 7200 NPE-G2 is a software switched router so any additional features enabled on the packet path increases the amount of CPU used. As to if this is reasonable or not, I suspect there are documents on the cisco site indicating the expected CPU utilization for a given featureset.offered load combination.

paolo bevilacqua · ‎11-28-2010

I suspect there are documents on the cisco site indicating the expected CPU utilization for a given featureset.offered load combinati

That is not the case, there are no such documents available, and everything is pretty much based on individual expereince and common sense.

paolo bevilacqua · ‎11-28-2010

witani wrote: