95
Figure 37
Network diagram for OSPF FRR
, 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 configuring OSPF FRR, complete the following tasks:
•
Configure network layer addresses for interfaces
•
Enable OSPF
Configure OSPF FRR to automatically calculate a backup next hop
Follow these steps to configure automatic OSPF FRR:
To do…
Use the command…
Remarks
Enter system view
system-view
—
Configure the source address of
echo packets
bfd echo-source-ip
ip-address
Required
Not configured by default.
Enter OSPF view
ospf
[
process-id
|
router-id
router-id
|
vpn-instance
vpn-instance-name
] *
—
Enable OSPF FRR to automatically
calculate a backup next hop
fast-reroute
auto
[
abr-only
]
Required
Not configured by default.
If
abr-only
is specified, the route to the
ABR is selected as the backup path.
Configure 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 the chapter “Routing
policy configuration.”
Follow these steps to configure OSPF FRR:
To do…
Use the command…
Remarks
Enter system view
system-view
—
Configure the source address of
echo packets
bfd echo-source-ip
ip-address
Required
Not configured by default.