quick spanning tree question

[cormon]

a client of ours had the following topology


4006 ------ 4506 ----- 3500.
------

They were moving the the 4506 up a few slots in a comms rack.
Since then they are having alot of network issues. There is only one LED on the 4506 module which is a wsx4306-GB 6. This is one of the cables going to the 4006 . There are two more fibre runs plugged into the 4506 in the equation that have no led on in their related ports , is this just an interface problem or is it possible that spanning tree has shut down one of the links to the 4006. I haven't got access to the switches till tomorrow.

Thanks in advance

 

[burtsbees]

If the 2 other links are also plugged into the 4006, and are not part of an etherchannel config, then yes, stp will block those ports if they are redundant.

Burt

 

[cormon]

Cheers Burt , the fact that the LEDS on the corresponding ports are off on the 4506 ,would this not indicate a cable or interface issue. As far as I know these should still be on regardless of spanning tree putting them into a blocked state.

Thanks....

 

[lerdalt]

definitely sounds like it could be that spanning-tree put the ports into err-disable. Been there a few times myself. Quick fix, is to unplug the gbic and plug it back in. Problem is, that it might drop again on you after spanning-tree converges, or another event occurs

But this is all a guess without access to logs or the CLI.

 

[cormon]

cheers lerdalt but again should the LEDS not be in a green state , the por being in blocked state should still have a link light ,

Kevin.

 

[burtsbees]

You only get a link light if BOTH sides are up---if one side is up and the other side is blocked, I am not sure...you'll have to get to the switches to be sure.

Burt

 

[lerdalt]

burt is right...if one side is blocked you may have an amber light, but I'm very confident that if a side is blocked there is no light.

 

[vipergg]

For some reason if they using the err-disable function those ports may have put into the err-disable state and the only way to fix this is to get into the switch and do a "shut" and then a "no shut" on the interface . It depends on how the err-disable function is setup , it can be setup for link flaps and at least a half dozen other symptoms that it can put it into a err-disable state like if you are using UDLD on the links.