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Interesting Issue

I'm having a unique situation. I have a network that has a pair of 6500 switches on either end, running HSRP.

In between each 6500 are two to three ruggedcom switches. They are connected to each other and the 6500's by trunk ports in a straight line. The 6500's see each other as CDP neighbors, and the 6500's can see the ruggedcoms as LLDP neighbors (ruggedcom only supports LLDP).

The issue is that randomly devices on the ruggedcoms will drop offline and then come back. The problem is that the devices that drop offline are all in the same VLAN, so it appears like a virus -  i.e. one device drops off, then multiple. Eventually the HSRP starts flapping between the two 6500s and this causes havoc on the network.

Can anyone think of an easier way (from the cisco side) to see how this traffic is propagating? I'm almost to the point of taking a laptop and plugging it into one of the ruggedcom's to see traffic, but the issue is that the ruggedcoms are outside in cabinets that laptops shouldnt be exposed to.

Thanks for all suggestions.

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Interesting Issue

Can you post a diagram illustrating the physical and logical topology?

In the meantime, have you noticed anything relevant in your log, such as spanning tree issues, interface transitions, unusual traffic spikes, etc?  The more detail you can provide, the better.

Interesting Issue

http://www.cisco.com/en/US/products/hw/switches/ps708/products_tech_note09186a008015c612.shtml

that is a way, but i would definitely prefer a capture session with Wireshark. The first method has a strong advantage.. it can be run for a longer period .

Another one would be to run NBAR for that VLAN and understanding what is going on from the statistics you will have after a couple of days..

check this out....

https://supportforums.cisco.com/thread/157605

And maybe you will change those switches in the middle one day

Alessio

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