MX HA PAIR || Routed Mode || Does it support Per VLAN HA in LAN

[vijaykumar]

Hello All,
I want to understand MX HA Pair in routed mode where we have 5 VLAN configured on MX device.

These 5 VLAN are configured & passed in L2 switch connected in LAN port of Both MX.

As per the Meraki Documents, It sends VRRP message for each VLAN in LAN segment and when Spare device does not receive these messages within certain time, It will take over active Role.

My doubt is, If I remove certain VLAN from intermediate L2 switch, in that scenario, Spare MX will not receive VRRP message. Will Spare MX work as Active device in HA for removed VLAN?

[alemabrahao]

No, removing a VLAN will not influence VRRP.

[KarstenI]

No, in case of a failure, the whole box will change the active state. There is no active-active operation on the MX.

[vijaykumar]

Thanks for your response.
Just to understand in more detail,
If I remove 4 VLAN out of 5 from L2 switch trunk port, leave only one VLAN passing through trunk, in this case also Primary MX will remain Active?

I am just trying to compare it with HSRP working.


In case of MX HA Pair,
How LAN devices [Host machine] will decide to send Data to Which MX? I mean who they will get ARP?

[KarstenI · Accepted solution]

The goal of MX HA is to deal with hardware failures. As long as the spare receives any heartbeats, no failover happens.

These heartbeats are L2 packets; the spare doesn't have an IP address. LAN devices always communicate with the device that holds the MX's LAN IP.

Here is some more information:

https://documentation.meraki.com/MX/Networks_and_Routing/Routed_HA_Failover_Behavior

[pdeleuw]

It's quite a long time ago, but one thing: The heartbeats are VRRP heartbeats, these are L3 packets. Source address is the address from the active MX. Destination is the multicast address 224.0.0.18. The spare MX does not have any LAN IP addresses, but it can receive the multicasts. So the only MX sending the heartbeats is the active one, the spare MX cannot send any IP packet.

[KarstenI]

Oh damn, of course, you are right. It is even clearly described in the link I added, but I messed that up. Thanks for the correction.

[IvanJukic]

Hi @vijaykumar ,

If you design your network right, you can have a single transit VLAN between the MXs via your switches. Then have the Switches act as Layer 3 routing devices between the downstream hosts and the MXs.

However, you really need to be careful how you can design this.

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