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Networking Issues

Posted on 2010-09-08
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Last Modified: 2012-05-10
We are a Cisco shop with a couple dummy switches all over campus. Today a 12-port dummy switch went down, and was replaced with a 24 D-link smart switch. The D-link replaced (2) 12 port dummy switches, when the d-link got plugged in both uplinks were plugged into the device... I believe causing a network/bridge loop?

After I got there and realized what happened I powered down the switch and disabled the 2 uplink ports on the Cisco box. However, its been hours later and the network is still acting poorly... like there still is a network loop.

The 6509 chasis is set as the primary root on all vlans. So i don't think STP would have re converged.

I've started to go thru the switches with cdp neighbor cmds and verify there are no loops still.  

Is there anything else I should be doing? testing? troubleshooting? Kinda clueless atm...
Thanks.
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Question by:PapaSmurff
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ludo_friend earned 500 total points
ID: 33633599
from what you've said - I wouldn't have thought you are still looped... but lets go though it anyway.

first up from your 6509 --

1 - check the backpane utilization
show catalyst6000 traffic-meter

2 - check STP for a vlan you are having trouble with. (assumed 1)
show spanning-tree vlan 1 detail

3- identify high utilization ports - run a few times and compare the results. this should identify your high talkers.
show interface | include line|\/sec

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Author Comment

by:PapaSmurff
ID: 33661778
Hey sorry for the disconnect.

Yes, our 6509 was running at 99% and their was high bandwidth coming down from one of our tengig links. Once I shut that port down the network came back to normal. The issue was a locked up 3COM 15 year old switch.

I'm guessing the broadcast storm caused an issue with various dummy/smart switches around campus because some of our nortel stacks needed a reboot as well.

Thank-you!
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Author Closing Comment

by:PapaSmurff
ID: 33661781
u da man!
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Expert Comment

by:ludo_friend
ID: 33667589
glad I could help!

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