Configuring Ospf Frr; Configuration Prerequisites; Configuration Guidelines; Configuration Procedure - HP HPE FlexNetwork 7500 series Configuration Manual

Configuring OSPF FRR

A link or router failure on a path can cause packet loss and even routing loop until OSPF completes
routing convergence based on the new network topology. FRR enables fast rerouting to minimize the
impact of link or node failures.
Figure 23 Network diagram for OSPF FRR
Router A
As shown in
hop. When the primary link fails, OSPF directs packets to the backup next hop. At the same time,
OSPF calculates the shortest path based on the new network topology. It forwards packets over the
path after network convergence.
You can configure OSPF FRR to calculate a backup next hop by using the loop free alternate (LFA)
algorithm, or specify a backup next hop by using a routing policy.

Configuration prerequisites

Before you configure OSPF FRR, perform the following tasks:
•
Configure IP addresses for interfaces to ensure IP connectivity between neighboring nodes.
•
Enable OSPF.

Configuration guidelines

•
Do not use the fast-reroute lfa command together with the vlink-peer command.
•
When both OSPF PIC and OSPF FRR are configured, OSPF FRR takes effect.

Configuration procedure

Configuring OSPF FRR to calculate a backup next hop using the LFA algorithm
Step
1. Enter system view.
2. Enter interface view.
3. (Optional.) Enable LFA on an
interface.
4. Return to system view.
5. Enter OSPF view.
Backup nexthop: Router C
Router B
Figure 23, configure FRR on Router B by using a routing policy to specify a backup next
Command
system-view
interface interface-type
interface-number
ospf fast-reroute lfa-backup
quit
ospf [ process-id | router-id
router-id | vpn-instance
vpn-instance-name ] *
Nexthop: Router D
Remarks
N/A
N/A
By default, the interface is enabled
with LFA and it can be selected as a
backup interface.
N/A
N/A
101
Router E