Troubleshooting, monitoring high utilisation on switches

Unanswered Question
Nov 8th, 2008

Hi guys,

We recently purchased a stack of four 3750e 48 Port Cisco switches that will eventually become the core of our network. The switch has 8 PortChannels connected to other switches in the network. At present the switch is only performing pure layer two functions. I am noticing that during the day the switch (stack) will hit 50/60% utilisation... now this may be normal but what concerns me is that the switch is not at capacity i.e each switchport is not occupied and as I say it is not performing any routing as of yet.

What is the best way to diagnose what is causing such utilisation? We make use of Op Manager and I we have snmp traps enabled for certain functions but neither are giving me what I want. What is even more concerning is that on Friday the network seemed to freeze for 30 seconds and then come back without any issue. What was frustrating for me is that 1) I did not know what had caused the problem 2) when others asked me I could not tell them (dont look very professional). Im pretty new to networking but am very intrigued and it is now my chosen career path! I just want to know more!! Im aware that this could have been caused by a switch or device elsewhere in the network but how do you diagnose this? I use the Cisco Network Assistant but often find that this gives different utilisation information compared to when I go into the switch from the CLI and review the CPU or memory utilisation.

Any pointers or tips would be much appreciated as always guys.

Thankyou

Darren :)

I have this problem too.
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