Configuring IPv4 FRR

Applicable Environment

If a link failure occurs after FRR is enabled, the fault detection module reports the failure to the upper-layer routing system. The FRR module immediately uses a backup link to forward packets, minimizing the impact of the link failure on services. IPv4 FRR applies to the services that are very sensitive to delay and packet loss on IPv4 networks.

IPv4 FRR implements route backup among routes of different routing protocols and may cause routing loops. Therefore, exercise caution when using IPv4 FRR.

With IP FRR, traffic is switched to a backup link if the primary link fails and switched back when the primary link recovers. If the inbound and outbound interfaces reside on different boards, packet loss may occur during the switchback. The packet loss duration varies with the service volume and CPU usage. To prevent the packet loss, perform any of the following operations:

• Run the timer spf command in the IS-IS view.
• Run the spf-schedule-interval command in the OSPF view.
• Run the route-select delay command in the BGP view.

Pre-configuration Tasks

Before configuring IPv4 FRR, complete the following task:

• Configuring link layer protocol parameters and assigning IPv4 addresses to interfaces to ensure that the link layer protocol of the interfaces is Up

• Configuring IPv4 routes destined for the same destination address but discovered by different routing protocols