Meraki MS390 (24 port) CONNECT to 2 Dell TOR Switches

[ShanePittman]

I have a conundrum that I am trying to work out. 

I have two MS390 24 w/8 port Fiber module.  (one active and one just sitting there as a backup) that connect my Dell TOR switches for VXRail to the rest of our network which happens to be MS225 48s.

Currently the two DELL TOR Switches connect to the Meraki MS390 via 4 10gb fiber cables, two from each dell switch. The dell switches, one is active and the other is failover. From the MS390, there are two 10gb fibers that connect it to our MS225 stack for the rest of our network.

I would like to set up the other MS390 as a failover for the current active 390 to minimize downtime, but I am not sure of the best way to go about it. I am not a networking person BUT I do have a MSP to help once I get direction on what my options are.

Right now our plan is to have the inactive switch configured the same as the active one and move connections from switch to switch if there is some sort of outage. Our experience has been that the VMs typically go offline for a while if there is firmware update and connectivity is lost for an extended time. im not sure if that is inherent to Meraki or if there is a configuration issues with the truck from the dells to meraki.

Thanks in advance for the help.

Shane

[cmr]

If the MS390 is performing layer3 (IP) routing then the only real option other than having an offline spare is to stack the two switches and then if either failed the other would keep working.  Firmware upgrades will take both down at once for about 5-10 minutes, though this is improving with the newer IOS-XE native firmware to about 4 minutes.

[cmr]

If the MS390 is not performing layer 3 routing, then you could just have the two switches in parallel.

[ShanePittman]

Hmm... This is intersting. How can i set this up? is there an article somwhere i can look at?

[cmr · Accepted solution]

If you mean in parallel, just set the ports up the same as each other and connect both ToR switches to them and also the MS225s to both.  Make sure that they have different spanning tree priorities with the existing one having the lower number.  Also make sure the Dell switches are set to MSTP.  The spanning tree protocol should close ports to stop a loop being created.  I would also link the two 390s together with a 20Gb portchannel so that that stays up and open in preference to the 1Gb and 10Gb other links.  To get the other switches to prefer the connection via the existing 390, you could make sure those are all portchannels (2x1Gb or 2x10Gb) with the connections to the secondary 390 being only single.  STP does generally prefer the faster connections.

I have done this on a smaller scale with three stacks of switches connected A-B 10Gb, A-C 10Gb and B-C 1Gb.  B-C was always STP disabled unless there was a problem with either A-B or A-C links.

[ShanePittman]

Nah. Layer 2 only.