Another ms425 question

[Marsrock2021]

If I use qsfp slot on my 2 ms425 slots to connect to vm network and 2 ms425 are stacked. Will I have to create a new stack on 4 std sfp ports (2 on each switch) to recreate stack.

Will meraki 0.5m dac cables doo for that. 

Is there any reason at all to stack 2 ms425 at all that are each connected to other building switches. 

[DarrenOC]

Hey @Marsrock2021 , the reason you would stack two switches is for resiliency. One fails, the other takes over.

[Marsrock2021]

But each of the building switches is connected to both of the ms425.If one ms425 fails will it not fail over to the other anyway

[MarcP]

depend on the devices connected to the switches. When you have a server which is only connected to one of the ms425, this server will be offline, for example when a buildingswitch goes offline.

If you stacked the ms425 this single armed switch will still be online.

Or using LACP would be a advantage as well

[Marsrock2021]

Thanks Guys.

I think I need to change the approach.

I currently have 2 MS425 stacked with 2 QSFP stack cables.

I need to add a seperate 40gb QSFP uplink to each MS425 but I dont have any spare ports as the stacking cables have them all used..

I either change the uplink to 10gb SFP+ and leave the 2 MS425 stacked with 2 QSFP stack cables.

Or add the 40gb QSFP uplink to each MS425 and change the stacking capabilities to 10gb.

Id prefer the 40gb QSFP uplink but cant find anywhere a Meraki SFP+ stack cable only the .5m Twinax Cable with SFP+. What cables is needed to stack the MS425 woth SFP+ ?

Bit silly that the QSFPs are all consumed with Stacking cables and none spare for an uplink.

[GIdenJoe]

I believe you can perfectly use 2x 10GB SFP+ ports for flexible stacking on the 425.

It does cut the bandwidth between members and can have oversubscription issues if you do so in a traffic dense environment.

If both MS425's are in the same rack you can use simple 10GB twinax cables to inter link both switches and modify those ports to stacking.  MA-CBL-TA-1M is the partnumber I believe.

Then you can use any kind of 40GB transceiver SR or BiDi or a 40GB DAC cable to link to the other devices.

Then you still have 2x 40GB uplink to other switches on the leftover two ports.

[Marsrock2021]

I think along the same idea as you.

Really strange that a unit like that if you stack you have no Uplinks. 

When most devices have rear stacking option. 

[Bruce]

The MS425 supports Flexible Stacking which means you can make any port a stack port. One of the benefits of this is that you can use any compatible transceivers or the stack - Twinax, QSFP, SFP+ - which gives some great options, especially for physically separated MS425 units. This is different to the rear stacking ports which generally only support the passive Twinax cables, and nothing more, so limiting you to a 3m cable.

[cmr]

@Bruce not really relevant here as we are discussing the 425s; but as far as I know you can use normal QSFP+ or QSFP28 transceivers in the rear facing stacking ports of the other Meraki switches.  So you could theoretically stack two MS355X-48s many miles/km apart...

[Bruce]

@cmr you are correct in that Meraki switches will physically accept standard QSFP transceivers in the rear stacking ports (since mechanically that’s all they are), but my understanding is it’s not supported, and in most cases won’t work - you’re pretty much restricted to the cables Meraki specify as ‘stacking cables’. With the Flexible Stacking on the MS425, Meraki fully support all the transceivers supported in the MS425 for stacking, so you can do long distance stacking if you want.

I’ve never tried to long distance stack anything other than a MS425 (which works fine), and above is consistently what I’ve been told by our local Meraki CSE team.