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Figure 110 Network diagram for IPv6 IS-IS FRR
In
Figure
110, after you enable FRR on Router B, IPv6 IS-IS FRR 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, IPv6 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 IPv6 IS-IS FRR in the following ways:
•
Enable IPv6 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 IPv6 IS-IS FRR, complete the following tasks:
•
Configure IPv6 addresses for interfaces to ensure IP connectivity between neighboring nodes.
•
Enable IPv6 IS-IS.
•
Make sure the backup next hop is reachable.
Configuration procedure
Configuring IPv6 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 IPv6 unicast
address family view.
6.
Enable IPv6 IS-IS FRR to
calculate a backup next
hop through LFA
calculation.
Backup next hop: Router C
Router B
Command
system-view
interface interface-type
interface-number
isis ipv6 fast-reroute lfa-backup
exclude
quit
isis [ process-id ] [ vpn-instance
vpn-instance-name ]
address-family ipv6 [ unicast ]
fast-reroute lfa
Next hop: Router D
Router E
480
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, IPv6 IS-IS FRR is
disabled.
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