Question on 7200/7500 series CPU usage levels

[KeithO]

I'm trying to get some information on a the CPU utilization levels to be expected from a Cisco 7200 or 7500 series router with an ACL in place. I'm looking for information specifically in the following areas:
1. How many packets per minute/hour (TCP, ICMP, UDP, etc.) will translate to what CPU utilization percentage? Is it a linear relationship?
2. Do routed packets have an increased/decreased affect on CPU utilization compared to packets denied by the ACL? For instance, would a volume of 20,000 packets per minute routed have a different CPU util level than 20,000 denied by the ACL?
3. Do packets of different sizes or protocol types have different levels of CPU utilization per packet?
4. During a DoS against my router, what number of packets per second/minute need to be sent to cause my CPU utilization to go to 100%? Does it matter if they are being routed or denied? This particular question comes up because it is my understanding that 200 denied "hits" per minute is "high", and that seems like a very low number of packets for this level of router.
Thank you very much for any information or insight you could provide on this.
Keith

 

[wybnormal]

This is tough to give "for sure" answers to. Many things can effect CPU utilization..

DLSW
Bridge groups
Access-lists
switch mode
Encapsulated protocols
routing protocols

These are just a few that come to mind. From what I've read, anything over 75-80% is considered high but ok if just a burst. substained utilization is a problem and you need to use the SHOW PROC CPU command to see what is sucking up the CPU cycles.

Mike S