IP FRR for static route entry

IP Fast ReRoute (FRR) is supported when the backup-next-hop command is configured for a static route entry. IP FRR support uses 1+1 protection by using a single backup next-hop address when the single primary next-hop fails. Only 1+1 protection is supported during backup without ECMP capability. Next-hop forwarding information for the backup next-hop address from the IP Routing Table Manager (RTM) is used to install a pre-resolved IP or tunneled fast reroute backup path to the backup next-hop. The configured backup next-hop IP address can be directly or indirectly connected through an IGP, a BGP, or a tunnel. The backup next-hop must be of the same IP address family as the primary next-hop (for example, an IPv4 primary next-hop can be protected using an IPv4 backup next-hop).

Note:

FRR for static route entries is only supported for IP traffic on FP-based platforms.

IP FRR for static route is supported in the base router and service VPRN contexts.

If the primary next-hop of the static route entry fails and the IP FRR backup next-hop is activated, then the backup tag is applied to the static route and the configured preference and metric for the primary hop is inherited. If the primary next-hop is activated again, then make-before-break functionality is used to avoid any packet loss.

The following is an example configuration for IP FRR:

static-route-entry 10.10.0.0/16
     tag 20
     backup-tag 100
     next-hop 101.1.1.1
          preference 100
          backup-next-hop
              address 50.1.1.2
          exit
      exit
     exit
  exit

The logic behavior applied to the associated tag of the static route entry is summarized in Table: Static route tag for IP FRR configuration .

Table: Static route tag for IP FRR configuration
Primary NH Backup NH

StaticRoute State

StaticRoute Tag

UP

UP

UP

201

UP

DOWN

UP

201

DOWN

UP

UP

1001

DOWN

DOWN

DOWN

—
Note:

  1. The tag value is based on the IP FRR example configuration provided above.

IGP export policies can use the tag and the backup-tag as match criteria when exporting a static route entry using route policies. The export policies may introduce unique export properties for each tag (for example, resulting in different IGP metrics) and may make an exported route more or less desirable when the primary next-hop fails and the backup next-hop is activated.

The following limitations apply in the IP FRR for static route entries.

Parent topic: IP router configuration