Flapping pc port causing network issues?

[bfpnetworking]

Yesterday, we had an unexplained networking issue.  We were getting general slowdowns and 4-6 percent packet loss to our core router.  AFter checking our wiring closet, I found one port flashing orange...then going greeen.....then flashing orange...I tracked this down to a computer that was in sleep mode, then coming out of sleep mode.  This was causing the NIC to initialize then go to sleep and repeat the processes every three minutes for 2-3 hours.

Could this type of an issue cause a slowdown?  If so, please help me to understand.  I can almost see where STP woudl have to communicate to each switch in the vlan, right?  Maybe it generated topology changes?  Not sure.

Thanks

[sdheer]

Hi,

From your description it looks like there could be some spanning tree related issue that could have occurred .

Did you check teh TCNs during the time issue was happening ,also did you see any kind of mac flaps on your swicth during that time.

However if the issue is now resolved it becomes difficult to track down if there had been any spanning tree issues during that time .Check the command "show spanning-tree detail " .

Also enable mac flap notification on your switch in order to see any host flaps happening in your netwrok.

Use the follwoing command in order to enable mac flap notification:

>> conf t

>> mac address-table notification mac-move

Hope that helps.

Regards,

Swati

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