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Frustrating Network or Switch issue

Senniger1
Senniger1 asked
on
Medium Priority
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Last Modified: 2012-08-13
Weird issue on my 3COM 3870 Gigabit switch...

Symptom: If I move a PC and connect it to another port on the switch, I get "limited or no connectivity" on the network properties and get no network access until I move the patch cable to another vacant port on the switch. Then, the PC will DHCP an address and connect fine. The port that is vacated stays "dead" until I reboot the switch. Typically, I do not move PCs a lot, however, users with laptops/docking stations have this issue every morning when they redock. The band aid fix is to move them to another port on the switch, but there are only so many open usable ports that I have until I am forced to reboot the switch.

I am clueless as to how to troubleshoot this. I thought perhaps the switch was keeping the ARP info from the previous port alive this blocking the new, but the MAC address is not even showing in the switch's ARP table. Any help or direction on where to take this would be most appreciated.
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SouljaSr.Net.Eng
CERTIFIED EXPERT
Top Expert 2011

Commented:
What about the switches mac address table?
SouljaSr.Net.Eng
CERTIFIED EXPERT
Top Expert 2011

Commented:
Do you clear it when this occurs?

Commented:
This is typical failure from overheating.
If it is under warranty then call 3Com and have them replace it.
Thanks,
Kelly W.
I agree with both of the last two posts.....if the switch is under warranty I would replace it, if it is not I would still replace it!  A switch is a major communication backbone to your network and if it is failing it is most likely a hardware issue within the switch.  I have never fixed a problem like this with a firmware upgrade, although if the unit is not under warranty you can try to upgrade the firmware and see it that solves it.  If this was my network I would replace the switch.

Commented:
Could be arp cache timout or could be a feature enabled called DUD (disconnect unknown device)

Author

Commented:
Both the overheating and firmware make sense as the problem. The switch is going on 7 years old and needs to be replaced. However, before doing that I will take a swing at updating the firmware to see if that helps at all. I will post back soon. Thanks for all the suggestions.

Question: Has anyone else seen this particular behavior on 3COM switches?

Commented:
I've seen it, but usually when that happened on my 3COM switches, it was the entire switch power cycling..  not individual ports.

ks_admin

Commented:
I have seen it when it was an overheating issue.
Thanks,
Kelly W.

Author

Commented:
Thanks.

There are actually two 3870's that are stacked, both appear to be having the same problem. On the firmware upgrade, do you know if I update the master if that will auto push to the slave? Sorry to ask this here, but I cannot remember when I did the upgrade last if I had to upgrade them individually or if the slave would pull the upgrade from the master. I will try it either way, but was just curious if you knew.

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