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2940 management interface seems to hang

Scott Fella
Hall of Fame
Hall of Fame

I have around 7 out of around 15 2940 that the management interface seems to hang. Traffice still passes, but you can't ping the management IP nor can you ping from the switch. All the interface are up up and even if I do a shut and no shut on the management interface (vlan 1) or on the gig uplink port, I still can't ping the management IP. The only way I get this to work is to reboot the switch. None of the ports goes into err disable so I don't know what is going on. Can someone give me some advice on this. Thanks.

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3 Replies 3

Level 3
Level 3

Scott :

You are likely running into a known Cisco software caveat CSCsb84292.

Release Notes:


A 2940 switch may stop receiving traffic on the control plane, while it is still able to transmit control

traffic (e.g. BPDU, CDP, etc). This affects functions that require traffic through control plane, such as

receiving spanning tree BPDU's, receiving CDP information from neighbors, receiving pings or ping

replies to the switch itself, receiving arp requests or replies for the switch itself, VMPS vlan resolution,

etc. Normal data flow through the switch between the physical interfaces that does not need to be

seen by the switch appears to be unimpacted.

Workaround :

Soft or hard resetting the 2940 restores the connectivity

Keep track of this bug through the bug toolkit as it is not still fixed and is still in the assigned state.

Hope this helps.

Salman Z.

Thanks alot!

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Level 1
Level 1

I have a similar problem on some physical interfaces: they work correctly but after some hours or days they stop to work. Interface seems up, with the correct mac address, no errors, input packets raise, but no output packet change. Stp, speed negotiation are correct. The other interfaces continue to work correctly. I need to reload the switch to solve the problem. IOS is C2940-I6Q4L2-M, Version 12.1(22)EA5. Any hints? Thanks