Network Desigh

[ATS55]

Hope Meraki experts take a look at this topic and share their thought with us

What I brought in the pic is just an example, but I have seen similar to these kind of set up in several companies.

Questions:

 However this type of setup works. What is the best practice of connecting the switches and MX?

I mean, it’s not a better idea if we connect MX to MS32P (distribution switch) then connect all department to MS32P.

If we follow this setup (in the picture) what Bridge Priorities should we assign to the switches?

I believe we should use MX only between distribution switch and ISP router. If it’s correct, so why MX designed with may Ethernet ports!

However these questions might seem silly, but your answers will help a lot of people. So, please contribute. Thank you all

[MartinLL]

Yes this is perfectly valid. In most cases of a network this size i would add a warm spare MX, create a stacked distribution and dual home both stack members to the MX.

https://documentation.meraki.com/MX/Deployment_Guides/MX_Warm_Spare_-_High_Availability_Pair 

Assign 2 bridge priorities if you run a stacked distribution. Low priority for your distribution switch and default for the rest. If you opt out of stacking and connect multiple switches to the MX just assign lowest and second lowest priority to the two switches closest to the MX.

The MX has multiple LAN ports for reasons you outline in your drawing. Multiple switches connecting, routed connections coming in on the LAN side, a third wan interface etc etc.

[PhilipDAth]

I'm not a fan of this type of approach.  The MXs are not spanning tree aware.  It puts a lot of reliance on spanning tree to correctly elect a root bridge via the shared MX fabric.

It often exposes spanning tree issues, and you can get great intermittent issues.

My strong preference is to use a stack of 1 to 4 switches as the core.  Plug both MXs into that.  Plug all downstream switches into those.  Make everything loop free.

I make the core switch stack have a bridge priority of 0.

I would not put a link directly between the MXs.  Once again, they are not spanning tree aware.  Removing that link will almost certainly prevent some future random outage.

[RWelch]

The default priority for all Meraki switches is 32768.

It is recommended that you set the priority of your desired root bridge to 4096 to ensure its election. The root bridge should be a switch in the center of the network, near high traffic sources (such as servers), to optimize traffic flow across the network. Using priority 0 is also acceptable for the root, but leaves no room for modification when replacing a core switch in production or modifying behavior temporarily.

It is best practices to set a layered approach to the STP priorities in a network.

For instance, if there is a clear Core <> Distribution <> Access Layer, priorities should be Core (4096), Distribution (16384), and Access (61440). At no point in a production network should you leave the any switch at its default configurations. 

Reference: https://documentation.meraki.com/MS/Port_and_VLAN_Configuration/Configuring_Spanning_Tree_on_Meraki_...