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The output interface of a BGP summary route is Null 0 on the originating router. Therefore, a summary

route must not be an optimal route on the originating router. Otherwise, BGP will fail to forward 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 specified route to make the specified route as the optimal route.

Configuring automatic route summarization

Automatic route summarization enables BGP to summarize IGP subnet routes redistributed by the

import-route command so BGP advertises only natural network routes.

To configure automatic route summarization (IPv4):

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. ip vpn-instance

vpn-instance-name

N/A

3. Enter BGP IPv4 unicast

address family view or

BGP-VPN IPv4 unicast

address family view.

address-family ipv4 [ unicast ] N/A

4. Configure automatic route

summarization.

summary automatic

By default, automatic route

summarization is not configured.

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.

To configure BGP manual route summarization (IPv4):

Ste