203
Controlling route distribution and reception
Configuration prerequisites
BGP connections must be created.
Configuring BGP route summarization
To reduce the routing table size on medium and large BGP networks, you need to configure route
summarization on BGP routers. BGP supports automatic and manual summarization modes. 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:
Step Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter BGP view.
bgp
as-number
N/A
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.
To configure BGP manual route summarization:
Step Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter BGP view.
bgp
as-number
N/A
3.
Configure manual route
summarization.
aggregate
ip-address
{
mask
|
mask-length
}
[
as-set
|
attribute-policy
route-policy-name
|
detail-suppressed
|
origin-policy
route-policy-name
|
suppress-policy
route-policy-name
]*
Not configured by
default.
Advertising a default route to a peer or peer group
After this task is configured, the BGP router sends a default route with the next hop being itself to the
specified peer or peer group. This action is taken regardless of whether the default route is available in
the routing table.
