R3102-R3103-HP 6600/HSR6600 Routers Layer 3 - IP Routing Configuration Guide

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Controlling BGP path selection
By configuring BGP path attributes, you can control BGP path selection.
Specifying a preferred value for routes received
This task allows you to modify the preferred value of a route to control BGP path selection.
Among multiple routes that have the same destination/mask and are learned from different peers, the
one with the greatest preferred value is selected as the route to the destination.
To specify a preferred value for routes from a peer or peer group:
Step Command Remarks
1. Enter system view.
system-view N/A
2. Enter BGP view or BGP-VPN
instance view.
• Enter BGP view:
bgp as-number
• Enter BGP-VPN instance view:
a. bgp as-number
b. ipv4-family vpn-instance
vpn-instance-name
Use either method.
3. Specify a preferred value for
routes received from a peer or
peer group.
peer { group-name | ip-address }
preferred-value value
Optional.
By default, the preferred value is 0.
Configuring preferences for BGP routes
A router can run multiple routing protocols with each having a preference. If they find the same route, the
route found by the routing protocol with the highest preference is selected.
You can use the preference command to modify preferences for external, internal, and local BGP routes.
By default, the preference of an EBGP route is lower than a local route. If a device has an EBGP route and
a local route to reach a destination, the device does not select the EBGP route. You can use the network
shortcut command to configure an EBGP route as a shortcut route that has the same preference as a local
route. The EBGP route is then more likely to become the optimal route.
To configure preferences for BGP routes:
Step Command Remarks
1. Enter system view.
system-view N/A
2. Enter BGP view or BGP-VPN
instance view.
• Enter BGP view:
bgp as-number
• Enter BGP-VPN instance view:
a. bgp as-number
b. ipv4-family vpn-instance
vpn-instance-name
Use either method.