MX warm spare routing

[cmr]

We currently have an MX250 in single arm concentrator mode terminating our SD-WAN site-site VPNs.  We have an additional MX250 with its own static IP connected internet connection but not added to any Meraki network.  When we go to set up the second device as a warm spare and pick the serial number from the list of available devices, we will choose the virtual IP.

The current active (to be primary) MX has an IP of n.n.n.201/24

The new (to be standby) MX has an IP of n.n.n.202/24

The virtual IP will be set as n.n.n.200/24

On the L3 switch stack that the MXs are connected to we have static routes for the subnets that are over the VPN pointing to the current active MX on IP n.n.n.201 as we are not using the OSPF advertisement option.

My question is, when we add the warm spare, will the existing traffic continue to pass via the n.n.n.201 address before we change the routes to point to the n.n.n.200 virtual IP?

My guess is that it would, but that is based on Cisco HSRP knowledge and I understand that the Meraki's use VRRP which of course is a generic version...

Thank you for your time,

Charles

[PhilipDAth · Accepted solution]

Yes - as long as the 201 address remains the active MX.

You would want to change over to the virtual IP as soon as you could afterwards though.

[cmr]

Thanks Philip, I hoped that'd be the case, we will of course change the routes ASAP but I want to drop as few packets as possible 🙂