Configuring IPv4 FRR

IPv4 FRR is applicable to IPv4 services that are sensitive to the packet loss and delay.

Usage Scenario

Public network IPv4 FRR is applicable to services that are sensitive to packet loss or delay on the public network.

After FRR is configured, if a fault is detected at the lower layer, the fault is reported to the upper-layer routing system. Then, packets are forwarded through a backup link, which minimizes the impact of link faults on ongoing services.

IPv4 FRR enables routes of different protocols to back up each other, which may result in loops.

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:

Configure parameters of the link layer protocol and IPv4 addresses for interfaces and ensure that the link layer protocol on the interfaces is Up.
Configure routes of different routing protocols but destined for the same destination address.

Procedure

Run system-view
The system view is displayed.
Run ip frr
IPv4 FRR is enabled.

If FRR is configured both in the system view and a routing protocol view, the FRR that is configured in the routing protocol view preferentially takes effect.
Run commit
The configuration is committed.

Verifying the Configuration

Run the following commands to check the previous configuration.

Run the display ip routing-table verbose command to check information about outbound interfaces and next hops of backup routes in the routing table.
Run the display ip routing-table ip-address [ mask | mask-length ] [ longer-match ] verbose command to check information about the outbound interface and next hop of the route matching the specified condition in the routing table.
Run the display ip routing-table ip-address1 { mask1 | mask-length1 } ip-address2 { mask2 | mask-length2 } verbose command to check information about outbound interfaces and next hops of routes matching the specified IP address and mask ranges in the routing table.