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, after you enable FRR on Router B, OSPF automatically calculates or designates a backup
next hop when a link failure is detected. Packets are directed to the backup next hop. At the same time,
OSPF calculates the shortest path based on the new network topology, and forwards packets over the
path after routing convergence.
You can either configure OSPF FRR to calculate a backup next hop automatically, or to designate a
backup next hop by using a routing policy.
Configuration prerequisites
Before you configure OSPF FRR, complete the following tasks:
•
Configure network layer addresses for interfaces.
•
Enable OSPF.
Configuration guidelines
•
Do not use FRR and BFD at the same time. Otherwise, FRR may fail to take effect.
•
Do not use the
fast-reroute auto
command together with the command
vlink-peer
.
Configuring OSPF FRR to automatically calculate a backup next hop
Step Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Configure the source address
of echo packets.
bfd echo-source-ip
ip-address
Not configured by default.
3.
Enter OSPF view.
ospf
[
process-id
|
router-id
router-id
|
vpn-instance
vpn-instance-name
] *
N/A
4.
Enable OSPF FRR to
automatically calculate a
backup next hop.
fast-reroute
auto
[
abr-only
]
Not configured by default.
If
abr-only
is specified, the route to the
ABR is selected as the backup path.
Configuring OSPF FRR to designate a backup next hop with a routing policy
Before configuring this task, you need to use the
apply fast-reroute backup-interface
command to specify
a backup next hop in the routing policy to be referenced. For more information about the
apply
fast-reroute backup-interface
command and routing policy configuration, see "
To configure OSPF FRR:
Step Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Configure the source address
of echo packets.
bfd echo-source-ip
ip-address
Not configured by default.
3.
Enter OSPF view.
ospf
[
process-id
|
router-id
router-id
|
vpn-instance
vpn-instance-name
] *
N/A
4.
Enable OSPF FRR to
designate a backup next hop
by using a routing policy.
fast-reroute
route-policy
route-policy-name
Not configured by default.