One lan/subnet out of several is not communicating

[Earl McEachron]

I have several vlans on a stack of 2 Cisco 3750G's. I can reach devices connected to all but one vlan. Nothing special is being done to that vlan. I also have other similar stacks configured similarly. They are working just fine. I can move the device to another stack and it works.

Does anyone have any idea where I should be looking for a resolution? Thanks!

[jmattbullen]

posting the config will probably be required.  but is the vlan interface up/up when you do a "show ip int brief"

[Andre Neethling]

Can you post the output of "sh spanning-tree vlan x" from the stack where it's not working, with x being the vlan that is not working.

[Earl McEachron]

Just saw your reply Andre. Thanks! I did do this and noted the strange behavior in my follow-on notes above. I disconnected the server and had the user delete the bridge. It works fine without the bridge.

I assume I would need to create a Port Channel to accommodate the bridge.

[paul driver]

Hello

Is the comunication failing throughout the lan of just in the this one stack?

sh vlan bri
st vtps status
 

res

Paul

[Earl McEachron]

I have found the issue. Not sure of the solution yet. But first, let me answer the questions posed below:

Paul - the communication fails in just this one stack.

Matt - there is no vlan interface; but, all the connected port interfaces are up/up.

The Issue:

      vlan 10 (offending vlan) is missing from the span tree forwarding state list.

      vlan 10 Root Role interface is an interface (g1/0/20) connected to a server rather than the

      uplink port channel (po8). The server owner attempted to create a bridge with two adapters on the server. Instead of causing an err-disabled, the switch changes the vlan Root role to one of the interfaces that the server's adapters are connected. BY un plugging the adapter at g1/0/20, the valn communicates again with the Root role returning to Po8.

This behavior is unfamiliar to me. If someone can explain this to me, I'd appreciate it. - Thanks!

[Earl McEachron]

I have found the issue. Not sure of the solution yet. But first, let me answer the questions posed below:

Paul - the communication fails in just this one stack.

Matt - there is no vlan interface; but, all the connected port interfaces are up/up.

The Issue:

      vlan 10 (offending vlan) is missing from the span tree forwarding state list.

      vlan 10 Root Role interface is an interface (g1/0/20) connected to a server rather than the

      uplink port channel (po8). The server owner attempted to create a bridge with two adapters on the server. Instead of causing an err-disabled, the switch changes the vlan Root role to one of the interfaces that the server's adapters are connected. BY un plugging the adapter at g1/0/20, the valn communicates again with the Root role returning to Po8.

This behavior is unfamiliar to me. If someone can explain this to me, I'd appreciate it. - Thanks!