Requirements for Routers with a Backup Router Configuration
If your Routing Engine configuration includes a backup-router statement or an inet6-backup-router statement, you can also use the destination statement to specify a subnet address or multiple subnet addresses for the backup router. Include destination subnets for the backup Routing Engine at the [edit system (backup-router | inet6-backup-router) address] hierarchy level. This requirement also applies to any T640 router connected to a TX Matrix router that includes a backup-router or inet6-backup-router statement.
If you have a backup router configuration in which multiple static routes point to a gateway from the management Ethernet interface, you must configure prefixes that are more specific than the static routes or include the retain flag at the [edit routing-options static route] hierarchy level.
For example, if you configure the static route 172.16.0.0/12 from the management Ethernet interface for management purposes, you must specify the backup router configuration as follows: