R3303-HP HSR6800 Routers Layer 3 - IP Routing Configuration Guide

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Controlling route distribution and reception

Configuring BGP route summarization

To reduce the number of routes to be redistributed and the routing table size on medium and large BGP

networks, configure route summarization on BGP routers. BGP supports the following summarization

modes: automatic and manual. Manual summary routes have a higher priority than automatic ones.

Configuring automatic route summarization

After automatic route summarization is configured, BGP summarizes redistributed IGP subnets to

advertise only natural networks. Routes injected with the network command cannot be summarized.

To configure automatic route summarization:

Ste

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. Configure automatic route

summarization.

summary automatic Not configured by default.

Configuring manual route summarization

By configuring manual route summarization, you can summarize both redistributed routes and routes

injected using the network command and determine the mask length for a summary route as needed.

The output interface of a BGP summary route is Null 0. With route summarization, BGP advertises fewer

routes to its peers. A summary route must not be optimal; otherwise, BGP will fail to forward the packets

matching the route. If a summarized specific route has the same mask as the summary route but has a

lower priority, the summary route becomes the optimal route. In this case, you must change the priority

of the summary or the specific route to make the specific route the optimal route.

To configure BGP manual route summarization:

Ste