H3C Technologies H3C S10500 Series Switches - Manual (Page 111)

96
Configuring OSPF FRR
NOTE:
•
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 commands vlink-peer, sham-link, enable
traffic-adjustment, and enable traffic-adjustment advertise (in the
MPLS Command Reference).
Introduction
When a link fails, the packets on the link are discarded, and a routing loop may occur until OSPF
completes routing convergence based on the new network topology.
You can enable OSPF fast reroute (FRR) to solve this problem.
Figure 37 Network diagram for OSPF FRR
In Figure 37 , 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 ] *
—