Greets long story short we had a power outage here and when the network came back online it would crash out to a flood of ARP requests.

This would lead to packet storm/network loop, but after careful auditing there appears no looping. I put an older 10/100 managed switch in instead of the gigabit switch that was acting up and it keeps the network up, however upon examining my wireshark readouts I've noted an STP error. I figure if I can fix the error I can switch back to the dumb+fast switch...

Here's a screenshot of some captured STP packets.

Here's a screenshot of a pre-STP network crash. 192.168.0.x doesn't exist on this network so that's kinda curious too..

I'd love to actually FIX this instead of simply solving the symptoms - thank you for your time! :D

  • 3
    Fix it by throwing out the dumb switches or taking them home for use in a small, personal network, which is the only place unmanaged network gear belongs. – HopelessN00b Feb 11 '15 at 0:34
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    Those aren't STP errors. Those are Frame Check Sequence errors, which are faults at the physical and data link layers. That may be corrupting the frames carrying the STP BPDU's, causing STP to not function properly. I noticed this is a 3Com switch. How old is it? Have you considered that this particular switch is the root of the problem? – joeqwerty Feb 11 '15 at 0:50
  • the 3com unit is the 'fix' insofar as the network functions with it connected - it's as old as time but without it everything comes grinding to a halt like in screenshot #2. Could some other device be causing the frame corruption and the 3com be detecting it? – BurntSilicon Feb 11 '15 at 6:35

The fix is to get rid of the dumb switch. That is a REAL fix. This is just an evil device waiting to make problems on the network which you will never be able to identify. Things will start being problematic in the strangest corners and everything will lead to software issues until one day, the switch will die. You will put a new switch in and not make the mental relation that forever after your removed that ... thing ... you are never called by the users complaining that things just freeze and don't work. Miracle!

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