Switchport showing UP / UP even when Administrative Down

[dtran]

Hello all,

I am running into an interesting issue on an old 48-port 3750 switch. I have a device connected to port 25 and suddenly it stops forwarding traffic even though the port is showing UP / UP and the link light is solid green (not blinking). So I move the device to port 35 and it came up working normally.

The interesting thing is that when I disconnected the device from port 25 but the port still showing UP / UP and the link light is solid green. So I admin down the port and it's still showing UP / UP and link light still solid green. And when I bring the port back up (no shut) the port status shows Down / Down but the link light still solid green until I plug in a device and it starts to blink normally and working normally. The port is now back to normal status.

Anyone seen this issue before ? what would cause the switch port to behave this way ?

In the switch logs I do see lots of link Up / Down messages on port 25 before it stops forwarding traffic.

Thank you all in advance for any inputs / suggestions !!!

Danny

[Reza Sharifi]

Hi,

If I remember correctly, this is bug in the IOS you are running. Try upgrading to a different version and test again.

HTH

[dtran]

Hello Reza,

I am running a pretty old version of IOS. I will look into upgrading the switch stack.

Thanks Reza !!! I appreciate your response !!

Danny

[Georg Pauwen]

On a side note, in addition to Reza's remarks, there are numerous bugs related to this issue...the recommended workaround is to reload the switch/stack, as this seems to be related to long switch uptimes...

[dtran]

Hello Georg !! Thanks for your response !!

The uptime on this switch stack is only 16 weeks as of today. Uptime might not be the case in this scenario.

Thanks !!!

Danny