• 1.  Inferior BPDU - STP-2-DISPUTE_DETECTED

    Posted 02-02-2021 00:17
    I'm hoping to find an answer to an issue I am having in regards to Spanning Tree and whether what I'm trying to achieve will work prior to planning a maintenance window to implement it.

    I have an issue where one network when I implement VSTP to be compatible with our core switches that are managed by a 3rd party and are Cisco Nexus switches running RPVST+ as they do by default.  I had set RSTP & VSTP up on this network but when I did the Cisco switches was seeing a dispute detected due to a Inferior BPDU being received.  I removed VSTP temporarily and I now have traffic passing.  However this network is required to be a loop not a star topology and currently I have had to disable a port in the loop to get it working until I can figure out how to make it redundant fully using STP(VSTP/RSTP).

    I have attached a diagram that hopefully explains the situation.  I realise I need to remove the MSTP component from Network A that is providing the infrastructure to this network(Network B) and no I cannot do a direct connection from the Nexus to the Network B. 

    Will I need to implement a native vlan(unable to use the standard VLAN 1) across all interswitch links so that the Nexus will properly detect any STP changes across the network from topology changes?

    When I change MSTP to VSTP/RSTP on Network A and re-introduce VSTP to Network B(yes it shows it in the diagram but not there due to this Inferior BPDU situation currently) will it clear this issue with the Inferior BPDU that arose as I had 4 STP protocols running:  RPVST+, MSTP, VSTP, RSTP across the network and MSTP & RPVST+ are not compatible as JTAC have informed me.

    I've used this KB article to assist with my understanding of what to configure but it seems to be missing some information, particularly around the native vlan requirements as one:  [EX] VSTP and RPVST+ convergence on native-vlan 1 - Juniper Networks

    The diagram also shows 8 VLANs presented from the Nexus that includes the 2 VLANs for Network B which I have notionally shown as VLAN ID's 7 & 9 though they are not the real ID's obviously.

    I'd be grateful for any assistance that can be provided.  Unfortunately config assistance or design assistance isn't really in JTAC forte as I have learned but still have a job open with them for issues while I wait for my account team.