Using both 40G and 10G ports in same stack

[nammah]

Hi,

Good day to all!

I have 4 x MS425 as core switches and MS350 as edge switches in the IDFs.

• 2 MS425 are stacked using 40G ports and is mounted in 1 rack which is considered as primary. Another 2 is stacked and mounted in another adjacent rack which is secondary.
• 2 MS350 in every IDF stacked physically. One uplink goes to the core stack in primary rack and 2nd uplink to the 2nd rack.

My query is:

1. Can I stack these 4 switches together to act as a single stack core; using 40G ports for the switches in the same rack and 10G ports to connect between inter-racks? And then aggregate the uplink ports on either ends.
2. If option 1 is not viable, the alternative would be to configure VRRP (warm-spare). Do I need to interconnect between the 2 stack pair of MS 425 using a dedicated cable?
3. If using VRRP, is it relevant to aggregate the uplink ports from the IDF and the corresponding ports on the core switches? or just configure them as uplink and leave it as it is.

thanks in advance.

[DarrenOC]

Hi @nammah , personally I’d have the MS425’s as a single stack with dual uplinks to each of the MS350’s.

Any reason why the MS425’s are dual split between two cabs?

[PhilipDAth]

>Can I stack these 4 switches together to act as a single stack core; using 40G ports for the switches in the same rack and 10G ports to connect between inter-racks? And then aggregate the uplink ports on either ends.

Yes, the MS425 will allow you to use both the 10Gbe and the 40GB ports for stacking at the same time.  You just have to mark the port as to whether it is doing stacking or not.

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

I do not know if you can aggregate stacking ports.

[nammah]

Hi @PhilipDAth 

Thanks and it should solve my problem.

Point about aggregation was not for stack ports, but for the uplinks from the IDF switches.

thanks,

[nammah]

Hi,

Just to be sure, is the below cable connectivity feasible with all ports configured as stack mode.

regards,

[GIdenJoe]

Hmm,

Although it does not say so in the documentation I would avoid mixing interface speeds in the same stack.

The only note in the documentation says this: Only 10Gb/s (SFP+) and 40Gb/s (QSFP) interfaces can be connected together as flexible stacking ports.

Unless a Meraki employee can shed the truth on this matter.

If you want to avoid having troubles I would recommend using only the 40 gig links for stacking so you have a single uplink speed in the stack.

Upper switch in rack 1 port 2 to upper switch in rack 2 port 1
Upper switch in rack 2 port 2 to lower switch in rack 2 port 1
Lower switch in rack 2 port 2 to lower switch in rack 1 port 1
Lower switch in rack 1 port 1 to upper swtich in rack 1 port 2

If the distance between the cabinets is not too large you could use 40G-BIDI SFP's so you only need the same amount of fiber strands for 40 G connectivity.

[nammah]

Thanks @GIdenJoe .

Purchasing new 40G BiDi SFPs cannot be easily done atm.

If mixing intf speeds is risky, I might need to compromise on the speed and use a full 10G only stack.

regards,

[GIdenJoe]

Or ask Meraki support about this.  I'm not sure how flexible, flexible stacking is 🙂

[nammah]

Hi,

Checked with the support and they informed that mixing of interface speeds is not allowed in a single stack.

thanks,

[SBINET]

Hi,

That's kind of strange cause I got the opposite answer from the support yesterday.

As they mentioned that is not recommended, but it work.

Here is the support answer:

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A new comment has been made on case 05476938:

Hello,

Thank you for contacting Cisco Meraki.

While it is possible to use a mix of 40G DAC and 10G SFP links, we do not recommend implementing this topology.

Regards,
Vijul Bhalla

[nammah]

Hi

UCcert

We  have around the 30 IDFs (2 towers) and the at the design stage,  the fiber uplink patch panels were split on to 2 racks for convenience.

regards