Switch on end of wireless bridge not receiving BPDU. Small switch thinks it is root.

[Einstein]

We have a small 8 Port MS210 switch in another building connected via 2 - MR76 wireless bridge with ANT-20 and ANT-23 antenna. 

The bridge, and connectivity have always been solid.  The issue we are having is the switch is not receiving any BPDU updates, so it always sets itself as the root switch in our org even though I have it manually set at 61440. 

So more than half of our network traffic is being sent across this wireless bridge, then back and eventually makes it to the true root switch (stack). 

There is a Cisco CBS switch between our main root stack, and the repeater. This switch RSTP is set correctly, and STP BPDU updates are getting through to the MR76 bridge, but the wireless bridge is not forwarding BPDU's across to the small 8 port switch. 

I know it's confusing, I apologize if my description isn't clear. 

I have been working with Meraki for several weeks now without any success. 

Very little traffic should be going here, but gigs are going across. 

Thank you in advance!

[alemabrahao]

I'm not sure, but although the documentation says that BPDUs should be forwarded, in practice, I understand that Meraki wireless mesh links don't provide transparent L2 bridging for STP, and BPDUs frequently fail to traverse the mesh.

[Einstein]

Totally agree.  Between Meraki and myself we cannot seem to find a fix for this.  I am investigating whether we need to replace the Meraki wireless (MR76) with Cisco Catalyst AP for a more robust, configurable connection. I hate to spend the money on this as the connection has been very stable. I have measurable latency on our network with this issue and need to get it resolved. When 75% of our traffic is going all the way across a wireless connection to another building, through a small 8 port switch then back, it's no bueno.

Thank you very much.

[alemabrahao]

Excuse the question, but wouldn't it be possible to extend fiber optic cable to L2?

[Einstein]

Fiber to our other building, unfortunately not an option. But yes, this would be ideal! 

[Ryan_Miles · Accepted solution]

@Einstein sending you a DM

[Einstein]

You're a rock star. Thank you for this information!

[alemabrahao]

Could you please share this information so it can help others who have questions about it?

[Ryan_Miles]

It's specific to the OPs Support case. Recommendation is if you're having this open please open a Support case for latest info.

[PhilipDAth]

On a side note, assuming there is only a single (WiFi) link between the two switches and just a single VLAN is being connected, and even if the MS210 was the spanning tree root - traffic would not trombone to the switch root and back again.

Spanning tree forms a loop-free network by blocking ports that would otherwise provide redundant paths.

If traffic was being tromboned, it wouldn't be because of spanning tree.  It would have to be because of something else in the network.

[Einstein]

Both Meraki and I have been performing packet captures, and yes we do have some traffic "tromboning", but yes, I agree with your explanation, but we do have 3 VLANS now configured across this bridge, and that has been working correctly.   I just think a new firmware, or unfortunately we will need to replace these MR76's with something more robust.  I can ping one of our root switches in the stack, and the entry will appear across the bridge on this remote switch. Traffic eventually finds its way, but we are experiencing periods of high latency.

Thank you everyone who has helped me with this. If we get to a solution I will come back and post.