Requirements and Best Practices When configuring routed HA, it is critical that both MXs have a reliable connection to each other on the LAN, so the heartbeats of the primary MX can be seen reliably by the spare. To ensure this connection is reliable: The two MXs should be connected to each other through a downstream switch (or ideally, multiple switches) on the LAN to allow for passing VRRP heartbeats. There should be no more than one additional hop between them, and they must be able to communicate on all VLANs. Make sure Spanning-Tree Protocol (STP) is enabled on the downstream switching infrastructure, as a properly-configured HA topology will introduce a loop on the network. When first configuring routed HA, the spare should be added and configured in the dashboard before the device is physically deployed, so it will immediately fetch its configuration and behave appropriately. Ensure that both MXs have their own uplink IP address for dashboard connectivity as mentioned here. If a virtual IP is being used, an additional IP address is needed, and all three IPs must be in the same subnet.
... View more
