H3C Technologies H3C S5560 Series Switches - Manual (Page 176)

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Step 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. IS-IS FRR uses BFD to detect
failures and enables fast rerouting to minimize the failover time.
Figure 39 Network diagram for IS-IS FRR
In Figure 39 , 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 might fail to take effect.
• The automatic backup next hop calculation of FRR and that of TE are mutually exclusive.