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,