I am getting ready to implement a vacl capture to send traffic to our IDS and NAM blades. We then have plans to use span sessions to send data to other products that will soon sit on our network. I am curious to learn how others measure the performance of their switches, specifically a 6513. Besides looking at PRTG stats, sh proc cpu, sh proc mem, looking for port errors, etc...

I am worried about the overhead that may come from doing the vacl capture and span sessions. What should I be paying attention to besides what I mentioned above? any other useful commands or tools that any of you guys use?

Thanks.