Hi Ibrahim,
Normally in high CPU issues I woudl suggest you open a TAC case, so that the engineer can investigate in detail the root cause of it, since there could be varied reasons for it. Just as an initial check you can monitor the follwoing things:
1. does the memory also spike when you experience high cpu.
2. does it cause any latency in the traffic.
3. amount of traffic hitting the firewall, is there some bursty traffic which causes the CPU to spike.
4. if there is a bursty traffic firewall would take time to process it, check the interafce errors as well.
5 check the connection count at the time of spike "show conn count"
6. check the connection details, if a particular host is sending multiple connection requests (identify any attack) "show conn detail"
You can provide all these details to the TAC engineer and would be helpful for troubleshooting it.
Hope this helps.
Thanks,
Varun
Thanks,
Varun Rao