Controlling Route Distribution and Reception 383
preferred-value preferred-value in Routing Policy Commands of the IP
Routing Volume.
Controlling Route
Distribution and
Reception
Prerequisites Before configuring this task, you have completed BGP basic configuration.
Configuring BGP Route
Redistribution
BGP can advertise the routing information of the local AS to peering ASs, but it
redistributes routing information from IGP into BGP rather than self-finding.
During route redistribution, BGP can filter routing information from specific
routing protocols.
Follow these steps to configure BGP route redistribution:
n
■ The ORIGIN attribute of routes redistributed using the import-route
command is Incomplete.
■ The ORIGIN attribute of networks advertised into the BGP routing table with
the network command is IGP. These networks must exist in the local IP routing
table, and using a routing policy makes routes control more flexible.
Configuring BGP Route
Summarization
To reduce the routing table size on medium and large BGP networks, you need to
configure route summarization on peers. BGP supports two summarization
modes: automatic and manual.
■ Automatic summarization: Summarizes redistributed IGP subnets. With the
feature configured, BGP advertises only summary natural networks rather than
subnets. The default route and routes injected with the network command
can not be summarized.
■ Manual summarization: Summarizes BGP local routes. The manual summary
routes enjoy higher priority than automatic ones.
Follow these steps to configure BGP route summarization:
To do… Use the command… Remarks
Enter system view system-view -
Enter BGP view bgp as-number -
Enable BGP to redistribute
default route into the BGP
routing table
default-route imported Optional
Not enabled by default
Redistribute routes from
another routing protocol
import-route protocol
[ process-id [ med med-value |
route-policy
route-policy-name ] * ]
Required
Not redistributed by default
Inject a network to the BGP
routing table
network ip-address [ mask |
mask-length ] [ short-cut |
route-policy
route-policy-name ]
Optional
Not injected by default
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