RSTP between Catalyst Switch and MS Switch

[meraki-newbie]

Dear All,

We want to make catalyst switch(Core) below as an RSTP root primary and secondary for several MS switches under the Core :

We have already state the all the MS switch RSTP priority to the maximum value of 61140

but, it seems the root switch still on each MS

is there any approaches to move the RSTP root to the Catalyst Core Switch, below a brief config on catalyst

glad to hear any response from you all

[ww]

Most convert to mstp on catalyst with meraki for stability.

But Rstp-rpvst should also work, it runs on  native vlan. (Doc says vlan1) https://documentation.meraki.com/MS/Port_and_VLAN_Configuration/Configuring_Spanning_Tree_on_Meraki_...

Do you have a trunk with native vlan on both sides?

[meraki-newbie]

so for stability we need to configgure mstp on catalyst?

yes we have already run native vlan 99 between ms <> catalyst trunk ports

but the root port not appearing at Catalyst, as we expected

[DarrenOC]

As per the note in the document provided by @ww switch to mst:

Note: To avoid unexpected issues where an MS is between two R-PVST switches (such as a Cisco Catalyst Root Bridge < MS > Catalyst switch). It is recommended to convert the topology to a MSTP on the Catalyst switches. This will avoid potential port inconsistency errors and other issues that may cause instability in the STP topology.

[meraki-newbie]

Alright,

so, with this topology below

MX1-MX2

|.           |

CAT1-CAT2

      \.   /

   MS125

we should set MSTP between 2 CATALYST (CAT1 & CAT2) setup the CAT1 as root & CAT2 as secondary root.. 

meanwhile on the MS125, just config RSTP with highest number priority available, so the forwarding path will be

CAT1-CAT2 

MS125-CAT1

and the blocking path will be

MS125-CAT2

is my understanding of the concept correct?

[RaphaelL]

CAT1 and CAT2 are not in a VSS configuration ?

[meraki-newbie]

for now we didn't use the VSS between CAT1-CAT2 (WSC3850)... should we set VSS the CAT1-CAT2 for better results?

[RaphaelL]

I couldn't see the model from your screenshot. These switches do not support VSS

[IvanJukic · Accepted solution]

Hi @meraki-newbie ,

As others have mentioned, it is recommended to run Multiple Spanning Tree on the Catalysts. As it is built upon IEEE 802.1D & IEEE 802.1w

You can achieve interoperability with RSTP & Rapid-PVST. However, it requires careful planning and configuration. See below excerpt from the guide below.

https://documentation.meraki.com/MS/Deployment_Guides/Advanced_MS_Setup_Guide#Protocol_interoperabil...

‘MS series switches can participate in spanning tree only when a spanning tree instance is running on Native VLAN of ALL switches. In addition, Native VLAN must be allowed on all Trunk ports running Rapid-PVST, so that BPDUs are seen by the Meraki switches in the topology.’

[meraki-newbie]

It works

the root bridge of MS125 is our Catalyst C3850 core..

we set up MSTP between C3850 .. 

Core 1 MSTP priority 4096

Core 2 MSTP priority 8192

All MS125 RSTP priority 61140

thanks all.. 

[IvanJukic]

Nice!!!!! Well done!.

[annmarie24us]

I agree with Ivan that ‘MS series switches can participate in spanning tree only when a spanning tree instance is running on Native VLAN of ALL switches. In addition, Native VLAN must be allowed on all Trunk ports running Rapid-PVST, so that BPDUs are seen by the Meraki switches in the topology.’