cisco nexus 9000 %STP-2-DISPUTE_DETECTED:

[shlomoi]

Hi ,

We recently connected a Maraki 9300L switch against our Nexus 9000.

A trunk al vlans is connected between them.
Nothing is connected to Maraki yet except the Nexus and we get error messages on the Nexus.

Does anyone have an idea what the problem is

error messages on nexus :

 %STP-2-DISPUTE_DETECTED: Dispute detected on port Ethernet1/10 on VLAN0012.
 %STP-2-DISPUTE_DETECTED: Dispute detected on port Ethernet1/11 on VLAN0013.
 %STP-2-DISPUTE_DETECTED: Dispute detected on port Ethernet1/23 on VLAN0014.

show spanning tree on nexus

n9k# show spanning-tree summary
Switch is in rapid-pvst mode
Root bridge for: VLAN0012, VLAN0013, VLAN0014,
L2 Gateway STP is disabled
Port Type Default is disable
Edge Port [PortFast] BPDU Guard Default is disabled
Edge Port [PortFast] BPDU Filter Default is disabled
Bridge Assurance is enabled
Loopguard Default is disabled
Pathcost method used is short
STP-Lite is disabled

spanning tree on meraki 9300L switch :

thanks

[alemabrahao]

What is the spanning-tree priority configured on Nexus? Have you tried setting it for zero?

[alemabrahao]

What about the native VLAN on the Nexus interfaces that are displaying the message, have you configured it?

[PhilipDAth]

>Switch is in rapid-pvst mode

It needs to be in MST mode.  Use this:
spanning-tree mode mst

All your Cisco switches should be set to use MST (in case you have others).

[GIdenJoe]

Yes put the Nexus switch into MST mode and have the MST0 instance on lower than default prio so it becomes the root bridge (unless you want the catalyst to be root bridge).

Once you do this the nexus will only send BPDU's natively and not send per-VLAN BPDU's which can cause many issues.

Then you can also set root guard on the ports on the rootbridge that go downstream to have a stable topology.

[shlomoi]

Hi,

this is an existing nexus with switches and servers connected to it, I'm afraid of making changes.
Why can't I leave the Nexus in PVST mode?
Is it possible to configure the Maraki in PVST mode ?

Thanks

[alemabrahao]

Please note: C9K/MS390 runs single instance (0), single region (region1), and single revision (revision 1) MSTP. This is essentially Rapid Spanning-Tree. Please make sure for interoperability with any other non-Meraki platforms, to either run Rapid Spanning-tree or MSTP (not PVST or any iteration, nor any other vendor specific STP implementation). This will ensure that there are no issues with compatibility and functionality.

https://documentation.meraki.com/MS/Port_and_VLAN_Configuration/Configuring_Spanning_Tree_on_Meraki_...)