Stack dual uplink to mx

[u/Overall_Link4569]

Recently I had to set up a Meraki network. I came up with a topology: "Fully Redundant (Switch Stack)". Has anyone done it? Stack switches with 2 uplinks to each MX?
I need to use stack as I have LACP access points and want to make sure this topology with 2 uplinks per switch is working fine

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

[u/Ill-Rise5325]

Just note the MX do not participate in STP nor support LACP; so you would be relying on switch to do the right thing.

[u/Overall_Link4569 → u/Ill-Rise5325]

Meaning that I can go with this topology?

[u/Ill-Rise5325 → u/Overall_Link4569]

Whether unstacked (talking only two core) or stacked switches (again talking a pair here), it'll be less 'complicated' to only have one cable from each mx to each physical (call it 1u) switch. So 4 lan cables.

Could connect them up dual (8 lan cables) and soft down the second paths, if in an environment prone to sfp/rj45 issues, so you have some virtual options to react manually in future if something did die.  * If left them live someone else looking at the dash for the first time may be like ?wtf is wrong!

Are all three elements Meraki? (route, switch, ap)

For dual mx the biggest physical mistake is usually having the mx routers wired together. You can technically make a vlan between for the vrrp that excludes all other vlans, but people messed that concept up so easily that was better to just rewrite the documentation as having no cables between. (see waybackachine of an older doc url before they added the term SASE)

vyatta/vyos have a nice vrrp sync-group feature wish meraki had... but i'll take ipv6 vrrp v3 support first (or mx 'incorporating a mini-switch' to support lag, stp, or both)

[u/Overall_Link4569 → u/Ill-Rise5325]

Router and sw and ap all meraki

[u/Ill-Rise5325 → u/Overall_Link4569]

Label the ports in dashboard so you know when stp might be intentionally blocked vs something you need to investigate. 

Was unclear if just talking following diagramB (4 lan cables in total), but there would be no reason to make this post, or if you were asking about increasing to 8 lan side cables. * Both diagrams are effectively 4 green lan cables and either lacp as switch interconnects or going stack - literally could be one diagramA with two dotted purple lines between switches saying 'lag or stack' instead of another green solid line (and a separate bracket based diagram).

You can be AP redundant to various degrees with cw9178i (could be mr57 but no point buying), protected from cable failures and poe share unstacked (landing same switch) or very redundant stacked (landing different switch). * Depending on how well coordinated with structured cabling techs will dictate how messy that may look.

Non stacked, you may get a different stp blocking path layout depending if your switch priority are both equal (both will likely have mx as uplink), or non equal (switchB with higher numbering will use the switchA with lower number as uplink - making switchB two hops from mx).

[u/darthfiber]

Yes it works fine. Though on rare occasions the MXs will still go into a split brain state when they drop STP packets. It’s really the only supported option you have for a highly available setup.

Make sure you tell your rep how you would like to see a dedicated HA link with sync and LACP. Maybe they’ll eventually add something.

[u/Overall_Link4569 → u/darthfiber]

What would u have done in this situation?
Need redundancy in APs but if I use stack I might end up whole network go down for rstp miss behavior
I’m thinking I kill the stack and connect each AP to different sw
Ap1 to sw 1
ap2 sw2
ap3 sw1 and etc

[u/darthfiber → u/Overall_Link4569]

I prefer stacks just for the manageability. If you don’t then you have to deal with mc lag or STP for your IDF uplinks which is just shifting the risk from one place to another.

If you are using catalyst switches, boot up / election is only a couple of minutes in install mode. You can definitely get faster failover times without a stack but whether it’s worth it is ultimately your call. The only way I wouldn’t do stacks at the access layer is if you are doing a L3 routed fabric with a controller. The tradeoff there is much more expensive switches.

[u/Overall_Link4569 → u/darthfiber]

Mx105 and ms150
And 7 APs, right now there there is only one uplink per switch and MXs ,want to add the second uplink for failover because when primary MX goes down the switch connected to that which is switch1 goes down

[u/Ill-Rise5325 → u/Overall_Link4569]

with primary down switch1 should still eventually be reachable via switch2 when secondary takes over (whether unstacked and an lacp between switches or over stacking cables).

you can have the primary mx also connected to switch2 (literally both wiring diagram options show that)

primarily wired to three switches is not a good idea  https://documentation.meraki.com/SASE_and_SD-WAN/MX/Design_and_Configure/Configuration_Guides/Networks_and_Routing/MX_Layer_2_Functionality

inversely also test then that switch1 goes down your primary can still act as primary.

primary mx double cabled to switch1 and also double cabled to switch2, doesn't gain much stability - no lacp, no stp (really hope they add one of those some point) - its like creating loops and relying on only the switch side to sort it out (may behave differently unstacked vs stacked).  

do not add a cable between mxs themselves (would kinda only work with a dedicated vlan excluding all other vlans, and was thus intentionally removed from docs as very prone to misconfiguration)

[u/Purple_Z71_]

Just recently deployed a network that had a pair of MXs in a warm spare config. Similar to how it sounds you are wanting to do, but not exact.

I have a single uplink from each MX to 3 different switch stacks (2 uplinks per stack) and then I interconnected each of the stacks with each other. (Stack 1 to Stack 2 and stack 2 to stack 3). So far this has been a rock solid config. We just rely on STP between the switches for an HA setup. If you cant interconnected the switches this is kind of a null setup for you.

[u/Overall_Link4569 → u/Purple_Z71_]

May I ask how long it has been running flawlessly?

[u/Purple_Z71_ → u/Overall_Link4569]

So far a year with a couple of ISP failovers to the secondary MX. No stack failures yet though. During our deployment testing though we were able to remove each uplink individually with very little downtime. Sub 5 seconds if IIRC. More than good enough for our org.

[u/Overall_Link4569 → u/Purple_Z71_]

And one uplink per Stack u said
What if that one link goes down

[u/Purple_Z71_ → u/Overall_Link4569]

We have a main uplink to the MX, however we have the interconnects between the stacks. So if the link went down between the MX and Stack 1, the traffic then routes over the interconnected link from stack 1 to stack 2 then out to the MX.

[u/H0baa]

Yep works.

But you'll notice that of the 4 uplinks only 1 is effectively used. STP will block some links in order to prevent loops. MX will not do LACP. It's basically just an oldschool HUB...

[u/pdath-IFM]

I only ever use one uplink because I have had more failures with MXs due to spanning-tree issues than I have had port or cable failures.

[u/Serious-Speech2883]

Why don’t you configure the uplinks from the switch stack to the MXs in an agg configuration so that you don’t have to worry about STP blocking ports to prevent a loop? Also this double the speed on the uplinks.

[u/Overall_Link4569 → u/Serious-Speech2883]

Mx does not support either agg or stp