Hello,
I'm having some troubles with rapid-pvst as randomly some switches are being isolated from the rest of the network for a specific singular VLAN.
The network segment that is interested by the problem is composed by a switch "A" connected to a core switch and a few peripheric switches across the site. There are a lot of VLANS configured, but I'm finding out since a few weeks that sometimes the periferic switches become "isolated" for a specific VLAN that we will call "VLAN 2". Every time I go to search the reason of that I find out that switch "A" blocked the link towards the switch (and the switch have the other ports blocked by itself or the other switches, so VLAN 2 stops communicating with the rest of the network). Initially I was just putting the interface on switch "A" manually in a forwarding state or rebooting the isolated switch to solve immediately the problem (so the link from the peripherical switch and switch "A" will stop to be blocked for VLAN 2 by switch "A"), but now a solution is needed.
The error on the switch "A" is: "Received BPDU with inconsistent peer vlan id 2 on Port-channel3 VLAN4"
Then, the switch blocks the VLAN 2 and 4 on the port channel3. Portchannel3 is the channel that goes towards the peripherical switch, that we can call switch "B". The logs are:
"Blocking Port-channel3 on 2. Inconsistent peer vlan."
"Blocking Port-channel3 on 4. Inconsistent peer vlan."
The port channel2 on switch "A" is in reality one singular port, and the switch "B" on the other end of the cable also has a port channel composed by only one port. This applies to this specific switch connection and all the other switch links towards switch "A".
Documenting myself I found out that it can be a native VLAN mismatch, but there isn't a native VLAN set on the ports, so they are using the default native VLAN. Then checking the configuration I saw that both switches allow on the trunk all of the existing VLANs of the network, no errors are displayed on the ports, the trunk in general is correctly configured.
The problem is always with VLAN 2 and VLAN 4, so the log is always the one reported previously, even if the network has a lot of other VLANS. Also the fact that different switches has the same problem was making me think that this is a problem that resides on switch "A", but I cannot find any helpful log.
All the switches are Cisco and the problem is manifesting randomly since a few weeks maybe once a month on a random switch. No changes were made to the network when the problem manifested itself for the first time, also in the previous month the configuration was the same as always. The switches are not rebooting or having links that change status before the appearing of the log "Received BPDU with inconsistent peer vlan id 2 on Port-channel3 VLAN4" so I'm at a point that thinking about something else is becoming difficult. I don't have physical access to the switches and my capabilities of asking for tests is limited, so if there is some check that I can do by myself that will not cause any disruption I can proceed, otherwise I would need to collect logs or evidence first to justify any tests. Could You kindly give me some suggestions?
Thanks
