Configuring Bgp Frr - HP FlexFabric 12900E Series Configuration Manual

Step
2. Enter
BGP-VPN instance view.
3. Enable BFD to detect the link to the
specified IPv6 BGP peer or peer
group.

Configuring BGP FRR

When a link fails, the packets on the link are discarded, and a routing loop might occur until BGP
completes routing convergence based on the new network topology.
You can enable BGP fast reroute (FRR) to resolve this issue.
Figure 63 Network diagram for BGP FRR
Router A
After you configure FRR on Router B as shown in
Router C for the primary route. BGP uses ARP (for IPv4), echo-mode BFD (for IPv4), or ND (for IPv6)
to detect the connectivity to Router D. When the link to Router D fails, BGP directs packets to the
backup next hop. At the same time, BGP calculates a new optimal route, and forwards packets over
the optimal route.
You can use the following methods to configure BGP FRR:
•
Method 1—Execute the pic command in BGP address family view. BGP calculates a backup
next hop for each BGP route in the address family if there are two or more unequal-cost routes
that reach the destination.
•
Method 2—Execute the fast-reroute route-policy command to use a routing policy in which a
backup next hop is specified by using the command apply [ ipv6 ] fast-reroute
backup-nexthop. The backup next hop calculated by BGP must be the same as the specified
backup next hop. Otherwise, BGP does not generate a backup next hop for the primary route.
You can also configure if-match clauses in the routing policy to identify the routes protected by
FRR.
If both methods are configured, Method 2 takes precedence over Method 1.
BGP supports FRR for IPv4 and IPv6 unicast routes, but not for IPv4 multicast routes.
To configure BGP FRR (IPv4 unicast address family):
BGP instance view
Backup nexthop: Router C
Router B
Command
•
Enter BGP
bgp as-number
instance-name
[ multi-session-thread ]
•
Enter BGP-VPN instance view:
or
a. bgp as-number [ instance
instance-name
[ multi-session-thread ]
b. ip
vpn-instance-name
peer { group-name | ipv6-address
[ prefix-length ] } bfd [ multi-hop |
single-hop ]
Nexthop: Router D
Figure
289
Remarks
instance view:
[ instance
]
N/A
]
vpn-instance
By default, BFD is
disabled.
Router E
63, BGP generates a backup next hop