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New Member

NAT and SIP

Hello,

I have router 2801 with IOS 12.4(3i). Configuration on router is dynamic NAT (PAT) for internet access and static NAT for SIP server. Every few minutes CPU goes to 100%, and the process responsable for that is IP INPUT (it uses 70% of CPU in show proc cpu).

When there is not SIP traffic CPU is fine but when SIP starts CPU usage is 100%. Ofcourse CEF is enabled.

Does Cisco router forward SIP traffic (in combination with NAT) using process switching or I'm experiencing IOS bug?

Router configuration is in attachment.

Thanks in advance,

A.

  • WAN Routing and Switching
5 REPLIES
Hall of Fame Super Bronze

Re: NAT and SIP

2801 is rated at around 46Mbps

http://www.cisco.com/web/partners/downloads/765/tools/quickreference/routerperformance.pdf

so if your throughput is around there, you are hitting the max in your router.

Care to post the show interface output from both FE when the CPU is hitting 100%?

___

Edison.

New Member

Re: NAT and SIP

Hi Edison,

Ofcourse I forgot to say that throughput on both interfaces is around 3Mbps

download and 1Mbps upload at all time. Also when CPU is hitting 100%

Regards,

A.

Hall of Fame Super Bronze

Re: NAT and SIP

You may be hitting a bug, try 12.4(15)T9 and see if it helps.

__

Edison.

Cisco Employee

Re: NAT and SIP

NATted SIP traffic is process switched.

New Member

Re: NAT and SIP

Hi,

This is normal behavior? Cause I can't find this in documentation.

Thanks,

A.

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