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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 assign a backup next hop for IS-IS FRR through the following ways:
•
Enable IS-IS FRR to calculate a backup next hop through Loop Free Alternate (LFA)
calculation.
•
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
The LFA calculation of FRR and that of TE are mutually exclusive.
Configuration procedure
Configuring IS-IS FRR to calculate a backup next hop through LFA calculation
Step
1.
Enter system view.
2.
Enter interface view.
3.
(Optional.) Disable LFA
calculation on the interface.
4.
Return to system view.
5.
Enter IS-IS IPv4 unicast
address family view.
6.
Enable IS-IS FRR to
calculate a backup next hop
through LFA calculation.
Configuring IS-IS FRR using a routing policy
You can use the apply fast-reroute backup-interface command to specify a backup next hop in a
routing policy for routes matching specific criteria. You can also perform this task to reference the
routing policy for IS-IS FRR. For more information about the apply fast-reroute backup-interface
command and routing policy configurations, see
To configure IS-IS FRR using a routing policy:
Command
system-view
interface interface-type
interface-number
isis fast-reroute lfa-backup
exclude
quit
a
isis [ process-id ]
[ vpn-instance
vpn-instance-name ]
b
cost-style { wide |
wide-compatible }
c
address-family ipv4
[ unicast ]
fast-reroute lfa
"Configuring routing
166
Remarks
N/A
N/A
By default, the interface
participates in LFA calculation,
and can be elected as a backup
interface.
N/A
N/A
By default, IS-IS FRR is
disabled.
policies."
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Troubleshooting
