HP 6125XLG Layer 3 - Ip Routing Configuration Manual page 262

You can enable BGP fast reroute (FRR) to resolve this issue.
Figure 61 Network diagram for BGP FRR
Router A Router B
After you configure FRR on Router B as shown in
for the primary route. BGP uses 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 after route selection.
There are two methods to configure BGP FRR:
Method 1—Execute the pic command in BGP address family view. BGP calculates a backup next
•
hop for a BGP route in the address family if there are two or more unequal-cost routes to reach the
destination.
Method 2—Execute the fast-reroute route-policy command to reference 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 and IPv6 multicast routes.
To configure BGP FRR (IPv4 unicast address family):
Step
1. Enter system view.
2. Configure the source address
of echo packets.
3. Create a routing policy and
enter routing policy view.
4. Set the backup next hop for
FRR.
5. Return to system view.
Backup nexthop: Router C
Nexthop: Router D
Command
system-view
bfd echo-source-ip ip-address
route-policy route-policy-name
permit node node-number
apply fast-reroute
backup-nexthop ip-address
quit
250
Router E
Figure 61, BGP generates a backup next hop Router C
Remarks
N/A
By default, no source address is
specified for echo packets.
Specify a source IP address that does
not belong to any local network.
For more information about this
command, see High Availability
Command Reference.
By default, no routing policy is created.
For more information about this
command, see Layer 3—IP Routing
Command Reference.
By default, no backup next hop is set.
For more information about this
command, see Layer 3—IP Routing
Command Reference.
N/A