%SW_MATM-4-MACFLAP_NOTIF - unstable link

[trevor.stuart]

We have a network with 1 core and multiple edge switches. There is an extension of this network across a wireless IP bridge(Dragonwave). 

The bridge is setup to function as a straight cable (vlan tagging and such is all done in the edge switches involved not in the dragonwave). 

All works great most of the time. However SOMETIMES when the bridge gets interrupted it sends the remote switch into some strange loop. This loop eventually ends with the switch out of memory and you cannot log in, even with the console cable. 

Power cycling the switch will SOMETIMES fix things, but not always. It can take a week of reboots before this remote switch smartens up and stops looping. 

Attached is my config file, and a few examples of the mac flapping error. 

Gi0/1 is the uplink to the rest of the network... 

The Fa involved is any active port on the switch with a device plugged in. There are no APs or switches of any kind on this remote switch... 

Any help or guidance is appreciated. 

[MHM Cisco World]

You have wireless brdige?

Can you draw topolgy 

MHM

[trevor.stuart]

This shows the topo... it's between switch 5 and 4 that the wireless bridge is in place. I have the uplink port on switch 4 disabled right now so the switch doesn't run out of memory that's why it's not showing them linked and it indicates switch 4 is off. But I can get into switch 4 via the console right now and re-enable the uplink anytime just starts the flapping as soon as I do and will eventually run out of memory. 

[MHM Cisco World]

The only solution I see is making direct link between two SW4 and SW5 with high cost so SW4 and SW5 select the direct link to Core as Root Port.

It issue of STP cost I think 

MHM

[trevor.stuart]

How would I do that? There is only 1 link between 4 and 5. Currently only 1 uplink port on both for this go-between. If/when I get this solved I'll look into a second port on each end for redundancy but right now just want to get this current issue cleared up. 

From what I understand STP does sound most likely, I just don't know what to do so switch 4 "cleans up" whatever is broken when the link returns. 

[MHM Cisco World]

Is below correct ?

MHM

[trevor.stuart]

No...The red uplink doesn't exist...

It's an IP link point to point and it's the only link between swtich 4 and the rest of the network. 

It's not excatly wifi either, as it's a licensed 15Ghz link but same idea in the end... That bridge is my uplink. 

I'm looking to change this but ran out of fiber between my core and where the bridge starts so my only option was to take a trunk port on switch 5 and make that the uplink to switch 4... 

[trevor.stuart]

As a test I set the uplink port (connected to the bridge) on switch 4 to have STP path cost of 4, and priority of 112 (all other ports are 19 and 128 respectively).

On switch 5 I set the uplink to switch 4 as cost 5 and pri 112, then the uplink to the core as cost 4 pri 96 (all other ports are 19 and 128). 

Enabled my uplink on switch 4 but am still getting the macflaps...  

[MHM Cisco World · Accepted solution]

share the output of  below
NOTE:- I start think it not issue of STP but other protocol make this flapping