Connecting MS425 between buildings

[Hubble]

Hi Experts,

We have two MS425-32 (core 1, core2) , stacks, use as core switches connected to access switches, in one building. We are moving a group of users to another building, just across the road. We're getting 2 new MS425 and will move existing access switch for the new building.

The plan is to connect the MS425s between building using mm fiber. So I'd just like to get more info on how the the SFP ports be configured. Am I going to add the 2 new switches as members of existing stack, can you stack between buildings? Or the new switches will l be a new stack? Can I use any ports on the MS425 to link to another MS425 between buildings, because currently ports 33, 34 are being used as stacking ports. 

Hope my questions make sense? Thanks in advance. 

Hubble

[kYutobi]

If I understand correctly you would just create a new stack on the 2 new switches and trunk/aggregate your fiber ports. 

[Hubble]

Thank you. So now I'm not  sure which ports to use, existing MS425-32 has ports 33 and 34 used as stacking ports between them. I thought I'd use those ports to connect to new switches. Can I use any port with SFP module?  Any example of port configuration to trunk or aggregate? Sorry I'm new to Meraki haven't done this before. Thanks. 

[kYutobi]

Im sorry @Hubble when say that you stack are you virtually stacking them or using a stack cable in the back.

[BrechtSchamp]

@kYutobi He's probably using Flexible stacking.

You could extend the stack to the other building. Today I assume there are two connections between the MS425 switches. To extend the stack you would take out one of those links liberating one stacking port on each switch. Those would each be connected to one of the new switches. Then similarly to the current situation, in the new building the new switches would also have a link in between them. Basically creating a square like shown below:

You can use any supported SFP (on both ends the same of course, and compatible with the fiber type). But note that only 10G and 40G link speeds can be used for the stacking. So take care about the distance between the two buildings and the supported speeds over those distances in combination with the type of wiring.

You could also just use an etherchannel between two switch stacks.

[kYutobi]

Thanks @BrechtSchamp for that. 

[Hubble]

Thank you. Yes I believe it is flexible stacking. Sorry I'm new here and the client is at different location. I only see diagram. 

Option 1 - Extend the stack to the other building - this may require downtime as we will take out one of the links from existing MS425s stack ports? Should I configure new switch ports as stacking ports first before making physical the physical connections? It will be a big help if I can get step by step instruction, but I will make more research as well.

Option 2 - Make the new MS425  as a new stack - keep the stack ports configued as they are for the existing MS425 and find available SFP ports to use to uplink to the new MS425 in the new building? Then trunk them?

Which is the better option?

[BrechtSchamp]

The instructions for option 1 are here:

https://documentation.meraki.com/MS/Stacking/Switch_Stacks#Configuring_a_Flexible_Switch_Stack

In my opinion there probably aren't many advantages of keeping both buildings as one stack. Unless you want to create a cross-stack etherchannel from ports in both buildings in case for example one of the buildings has a power issue.

It's all a matter of how you want to setup your redundancy.

[kYutobi]

I agree with @BrechtSchamp on this one. It seems a better option "if" you want to keep the stack.

[Hubble]

Thank you for your response

[Hubble]

Thanks again @kYutobi  and @BrechtSchamp ,

Here are more details of the equipment:

Existing:

(2) MS425-32 -- 32x10G SFP+fiber ports , 2x40G QSFP+ uplink/stacking ports

New:

(2) MS425-16 -- 16 x 10G SFP+ fiber, 2 × 40G QSFP+ uplink/stacking ports 

Currently,  MS425-32 are using the 40G ports as stacking ports between them. So I'm just not sure which ports I can use to uplink the existing MS425 to the new MS425 in the new building. What do you think? 

[GIdenJoe]

If you really need to extend your L2 domain then you could expand you stack. If not make 2 distribution blocks andconnect them L3.

[Hubble]

Thanks @GIdenJoe ,

Since the 40GB ports are being used as stack ports, I'm thinking of making any available 10GB ports as L2 uplink ports to connect MS425 between building. The new building is just across the road and we'll run mm fiber to it from the old building. Does that sound a good solution? 

[BrechtSchamp]

Only you can be the judge about what bandwidth you would need between the buildings. But a 20G etherchannel is probably plenty in most cases.

Between the buildings I would install single mode fiber if I were you (and foresee more fibers than you need). The cost difference will not be that big and you'll be more futureproof. MM fiber should only be using within buildings. Distances are limited over MM fiber when using higher speeds.

[Hubble]

Thanks @BrechtSchamp 

I just took over this project and the previous engineer left the company,  he placed an order for 40GB fiber transceiver already and will use MM fiber as the distance is less than 300m. So looks like the plan is to use 40GB between buildings and I just don't know if we can still do that after I found out last week that 40GB ports are being used as stacking ports.

But for plan B, I'll just use two 10GB ports as etherchannel, however I don't see that option from the Meraki GUI portal, ports configuration , do I have to do it from the command line? 

[Hubble]

Thanks @BrechtSchamp 

[BrechtSchamp]

To combine two (or more) ports into an etherchannel, go to Switches > Switch Ports select the two ports you want to combine and press the "Aggregate" button. It will only become available when you select ports that are configured identically.

[Hubble]

Got it, thanks @BrechtSchamp 

Just in case they insist they want to use the 40GB ports, what options do we have since those ports are being used as stacking ports? Use physical stacking to release those ports? 

[BrechtSchamp]

MS425 doesn't do physical stacking, only flexible stacking. So the only option you would have then is to move over the stacking to 10G ports thus freeing up the 40G ones for the link(s) in between the buildings.

[Hubble]

Oh okay, thanks @BrechtSchamp . Sorry I did'nt know I can use any 10GB ports as stacking ports. 

So is it as easy as selecting Enabled from the switch port Meraki portal and then move the stacking cables to them? Can I use the same cables? I guess there will be downtime during the move. 

[BrechtSchamp · Accepted solution]

There will be downtime yes. You will likely have to rebuild the stack from scratch, so note down how the ports are configured before doing anything.

You'll indeed have to enable stacking on the 10G ports, but you will probably have to disable it on the 40G ones first.

40G uses QSFP and 10G SFP+. You'll need different transceivers. You can reuse the patch cable itself.

[Hubble]

Thanks @BrechtSchamp 

[Aboobacker]

@BrechtSchamp  A correction on the thread !!

Meraki MS425 supports both physical and flexible stacking.

Physical stacking of up to 8 switches with 160 Gbps stack bandwidth, while flexible stacking on all interfaces and SFP+/QSFP+ accessory types, up to 8 switches.

https://meraki.cisco.com/product-collateral/ms425-series-datasheet/?file

Page no.5 in the above datasheet briefs about this.

[BrechtSchamp]

@Aboobacker Thanks for your post. What I meant with that statement is that the MS425 doesn't have dedicated stacking ports, which means for the stacking you need to use the actual ports on the switch. So if you want a 40G stack you're using up those ports and you can't have a 40G uplink anymore. But you're right I worded that incorrectly. It's still physical stacking, just not with dedicated ports.

[Hubble]

Thanks so much

. So seems like Option 2 is a better option for me. So can I use any available SFP ports on MS425 to connect to new MS425 switch in the new building? Existing MS425 has two ports with 40Gps speed and they are being used as stacking ports. I thought we should use those ports to interconnect to the other building. Yes?

[Hubble]

I believe it's Flexible stacking using 2 ports in the front as stacking ports