212
Step Command
Remarks
4.
(Optional.) Enable default
route redistribution into
BGP.
default-route imported
By default, BGP does not
redistribute default routes.
Controlling route distribution and reception
This section describes how to control route distribution and reception.
Configuring BGP route summarization
Route summarization can reduce the number of redistributed routes and the routing table size. IPv4 BGP
supports automatic route summarization and manual route summarization. Manual summarization takes
precedence over automatic summarization. IPv6 BGP supports only manual route summarization.
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 specific route to make the specific 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 unicast/multicast address family):
Step Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter BGP IPv4 unicast
address family view,
BGP-VPN IPv4 unicast
address family view, or
BGP IPv4 multicast
address family view.
•
Enter BGP IPv4 unicast address family
view:
a.
bgp
as-number
b.
address-family ipv4
[
unicast
]
•
Enter BGP-VPN IPv4 unicast address
family view:
a.
bgp
as-number
b.
ip vpn-instance
vpn-instance-name
c.
address-family ipv4
[
unicast
]
•
Enter BGP IPv4 multicast address
family view:
a.
bgp
as-number
b.
address-family ipv4 multicast
N/A
3.
Configure automatic
route summarization.
summary automatic
By default, automatic route
summarization is not
configured.
