How to measure Layer 2 vlan Utilization?

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Mar 31st, 2008
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I have a pair of 6500 switches with SUP720's and I'm wondering if you have a layer 2 vlan trunked between the two switches and your trying to diagnose Utilization issues:

How do you measure that?

I know you could look at the port-channel that is trunking between the two switches but that really won't tell you to much because it will be in relation to ALL the links and ALL the vlans going over the port-channel.

There is no interface to show you basic counter information like you get when you have an SVI for your vlan.

So does that mean that theoretically the limit of how much traffic the layer 2 vlan can switch is as fast as the backplane of the switch?

Outside of doing show commands on the actual host facing interfaces withIN the vlan, I can't think of a way to measure how congested or busy the switch is with processing traffic from that vlan.

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Rick Morris Tue, 04/01/2008 - 08:45
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Do you have a sniffer?

You could span that trunk port and capture the data there and depending on the sniffer you may even have a dashboard to view. You might want to look at Ethereel, not sure of the spelling, but I believe that is free and might help point you in the right direction.

decibel101 Tue, 04/01/2008 - 08:48
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HA! One step ahead of you!

I have a vlanspan going for the whole vlan to look at some traffic.

The only other options I came up with are the following commands, which really in effect give you an outlook on the overall swtich health.

sh platform hardware capacity fabric

sh platform hardware capacity forwarding

sh platform hardware capacity cpu

sh platform hardware capacity eobc

sh platform hardware capacity interface


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