Cisco 3850 Access layer switch connection to Meraki 425 core switch

[MR]

Guys.

Do you foresee any technical issues if i have few stacks of Cisco IDF access layer 3850 connect to Meraki MS425 which will act as a core switch? basically 2x 425 acting as core and few IDF 3850 will be connecting to the MS425.

Please advise. Thanks

[Bruce · Accepted solution]

The main issue you’ll likely encounter will be the wonders of spanning-tree (STP). Cisco, by default, runs Rapid-PVST+, Meraki uses standard RSTP. With the default setup you need to have the Cisco switch as the STP root, otherwise it all gets a bit hairy.

Best solution is to swap the Cisco switches over to MSTP (sometimes written as MST) and use that, then they should interoperate seamlessly with the Meraki switches running RSTP - MSTP and RSTP are both standards and interoperate; PVST and its variants are Cisco proprietary and don’t interoperate as well as they potentially should.

EDIT: there’s more detail on STP interoperability here, https://documentation.meraki.com/MS/Deployment_Guides/Advanced_MS_Setup_Guide

[DarrenOC]

Hi @MR , also note that MSs don’t support VTP but they will forward VTP updates. 

We have this setup (MS at core and legacy Cisco at the edge) across numerous sites as customers start their journey to a full meraki network.  As @Bruce mentions you’ll need to configure a single MST instance  on your Cisco switches.