Spanning Tree Issue - Maybe

Question

Hi there,Trying to figure out a really odd issue. This particular network has been running fine for ages with no issues at all. All the switches are N3024's either in single, double or triple stacks. I have one switch in the network that has suddenly starting dropping off the network.There are three links into the switch, one fiber and two Microwave to ethernet and when the switch drops off I found that cycling the links at the other end would bring the switch back up. Further diagnostics show that if I leave one of the Microwave link ports disabled at the other end the switch stays perfectly stable. Enable that link and almost immediately the switch drops off the network.Nothing has changed with regards firmware (although they do need updating) but I can't see why all of a sudden this one switch has started playing up. I also swapped the switch out for another one just in case it was a hardware fault but I'm seeing exactly the same behavior on the switch I've put in which makes me think it's some sort of config issue. Any thoughts?

DELL-Josh Cr · Accepted Answer

It does seem like it is something with port 22, what is it connecting to?

DELL-Josh Cr · Answer

Hi, Are there any other errors in the logs? It does sound like it could be spanning-tree and then shutting down ports. Is this one is a stack and is it the master? You may also want to check cabling.

JasonCoretek · Answer

Single switch in this case and it's been swapped out for an identical switch but still exhibits the same problem. Anything specific I should be looking for in the logs that would help? I can easily clear the logs and then replicate the issue by turning the third link back on.

JasonCoretek · Answer

So I've just re-enabled the link (with a ping running to the switch) and within seconds it dropped off. Left it like this for a couple of minutes then disabled the link and within about 45 seconds it started responding again (Log info below)

Notice	Jul 24 09:19:59	TRAPMGR	Gi1/0/22 is transitioned from the Learning state to the Forwarding state in instance 0
Notice	Jul 24 09:19:59	TRAPMGR	Gi1/0/22 is transitioned from the Forwarding state to the Blocking state in instance 0
Notice	Jul 24 09:19:55	TRAPMGR	Gi1/0/23 is transitioned from the Learning state to the Forwarding state in instance 0
Notice	Jul 24 09:19:53	TRAPMGR	Spanning Tree Topology Change: 0, Unit: 1
Notice	Jul 24 09:19:53	TRAPMGR	Gi1/0/22 is transitioned from the Learning state to the Forwarding state in instance 0
Notice	Jul 24 09:19:52	TRAPMGR	Gi1/0/23 is transitioned from the Forwarding state to the Blocking state in instance 0
Info	Jul 24 09:19:37	CLI_WEB	[WEB:Coretek:10.10.80.12] Disconnected due to Idle Timeout
Notice	Jul 24 09:17:08	TRAPMGR	Gi1/0/22 is transitioned from the Forwarding state to the Blocking state in instance 0
Notice	Jul 24 09:17:08	TRAPMGR	Spanning Tree Topology Change: 0, Unit: 1
Notice	Jul 24 09:16:57	TRAPMGR	Gi1/0/23 is transitioned from the Learning state to the Forwarding state in instance 0
Notice	Jul 24 09:16:55	TRAPMGR	Spanning Tree Topology Change: 0, Unit: 1
Notice	Jul 24 09:16:55	TRAPMGR	Gi1/0/22 is transitioned from the Learning state to the Forwarding state in instance 0
Notice	Jul 24 09:16:54	TRAPMGR	Gi1/0/23 is transitioned from the Forwarding state to the Blocking state in instance 0
Notice	Jul 24 09:12:18	TRAPMGR	Spanning Tree Topology Change: 0, Unit: 1
Notice	Jul 24 09:12:18	TRAPMGR	Gi1/0/22 is transitioned from the Forwarding state to the Blocking state in instance 0

JasonCoretek · Answer

Port 22 is a direct link to one of the two Microwave RFU's. Currently on that switch there are two microwave links and a fiber link with additional ports linked to the management port of the Microwave RFU's. I just downed the port to make sure that neither of the management IP's dropped, which they didn't, so that tells me it's the RFU Data link. I know it's not a management issue as we have turned off all the MSTP options on all the Microwaves in the network to allow the switches to manage Spanning tree. That tells me it could be an issue with the Microwave RFU which I can raise with the maintainer. Thanks for the pointer.

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