R21xx-HP FlexFabric 11900 Layer 3 IP Routing Configuration Guide

139

Ste

Command

Remarks

1. Enter system view. system-view N/A

2. Enter interface view.

interface interface-type interface-number N/A

3. Enable IS-IS on an interface.

isis enable [ process-id ] N/A

4. Enable BFD on an IS-IS

interface.

isis bfd enable

By default, an IS-IS interface

is not enabled with BFD.

Configuring IS-IS FRR

A link or router failure on a path can cause packet loss and routing loop. These problems can continue

until IS-IS completes the routing convergence based on the new network topology. IS-IS FRR enables fast

rerouting to minimize the impact of link or node failures.

Figure 36 Network diagram for IS-IS FRR

In Figure 36, after you enable FRR on Router B, IS-IS automatically calculates or designates a backup next

hop when a link failure is detected. In this way, packets are directed to the backup next hop to reduce

traffic recovery time. Meanwhile, IS-IS calculates the shortest path based on the new network topology,

and forwards packets over the path after network convergence.

You can either enable IS-IS FRR to calculate a backup next hop automatically, or designate a backup next

hop with a routing policy for routes matching specific criteria.

Configuration prerequisites

Before you configure IS-IS FRR, complete the following tasks:

• Configure IP addresses for interfaces to ensure IP connectivity between neighboring nodes.

• Enable IS-IS.

Configuration guidelines

Do not use FRR and BFD at the same time. Otherwise, FRR may fail to take effect.