Ok I'm new to MicroTik (formerly UBNT) I'm sure I'm missing some mundane detail and at my wits end.

I am trying to wirelessly bridge 2 network segments with vlans. building A to Building B. I'm configuring to leave the ability to add building C.

Cisco2960 Switch's, IOS 12.2+, and 15.0+, stripped to default in isolation from rest of network.
Ports configured as Trunk with native vlan on each. connection works fine when using a cable and I can connect to production no issues.

MicroTik QRT 5 AC 6.40.3 and a separate pair (4) at 6.43.8
Unit 1 is configured as WISP AP from quick set
Unit 2 is configured as CPE from quick set

units see each other just fine, a client on the end of the CPE works fine.

When I install the switch for the CPE end "all hell breaks loose".
The CPE switch promptly err-disables the port due to loop back detection. I can suppress this by disabling keepalives on the switch...
The WISP AP side sees a fight over who is the STP Root Bridge.... my desired root bridge is set lower so this should never happen.

I set STP on the MT's higher which seems to have suppressed the STP issue.

I though I had it working until I went to production and discovered that on GbE switches (aka not the junk in the lab) no keepalive is gone... so I've brought the network to its knees twice today.

Ideas? Only thing I have left is the MT is interacting with the network such as to reveal and existing problem that for whatever reason causes no err-disables without the MT's....only thing coming to mind here is potential for RSTP diameter is stabbing me in the back....(MT's are 2 more hops?)

I'm not sure if that Quickset-CPE setting is the setting you want.
Leave quickset aside, remove both configurations and start from scratch:

On the AP side, create a bridge, add wired and wireless interfaces to it.
Completely disable any flavor of STP on the bridge.
Set your wireless interface to ap-bridge.

Do the same on the client side and set the w/l interface to station-bridge.

I had some STP-issues with older firmware (must have been 6.38 or so) when connecting two Cisco switches (these were Catalyst 9300 in my case). I had to disable discovery on the bridges and additionally drop input packets to 01:80:C2:00:00:00, :03,and :0E in bridge filters. That solved my issue back then but I don't know if that's still the case.

Good luck,
-Chris

Thanks Chris,

I've left the existing config for now as the Quick Set - CPE does set it to station bridge.

I have now disabled STP on the bridge as well as loop protection on ether1. There was another STP Storm today so it is clearly ignoring bridge port priorities. (cisco are at default 8000, core switch at 4000, and the MicroTiks were at C000...

unfortunately it completely behaves in isolation, and I'm not keen to test in production right away.

I have seen this before with UBNT bridges so not surprising...will advise.

ok with STP disabled on the bridge I was still getting topology changes every 5 min.

so now looking at the AP log I see a lot of disconnected, extensive data loss. Followed by connected, wants bridge. these appear to coincide with the topology changes.


TX/RX is at -27/-27
Signal to Noise is 74 dB
CCQ is 95%+

By all accounts this should be a solid connection...but... jumping over to the CPE (station bridge) I now notice RX Rate is flapping between 866Mbps and 6Mbps...

-27dB is way too loud. They are screaming at each other.
Even for a lab - increase the distance between the two units drastically.
I'm pretty sure that's one (or even your only) of your problems.

Flapping data rates are pretty normal when being mostly idle.

-Chris