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Command Reference Guide
Usage Examples
The following example configures this BGP neighbor's AS number on the default VRF instance to be 300:
(config)#router bgp 100
(config-bgp)#neighbor 192.22.73.101
(config-bgp-neighbor)#local-as 300
The following example configures this BGP neighbor's AS number on the nondefault VRF instance named
RED1 to be 300:
(config)#vrf RED1 route-distinguisher ip 192.17.250.24:33
(config)#router bgp 100
(config-bgp)#vrf RED1
(config-bgp-vrf)#neighbor 10.20.1.1
(config-bgp-vrf-neighbor)#local-as 300
Technology Review
This router appears (to the peer router) to be in the AS specified with the local-as command. Therefore, all
routes learned from the peer have this number prepended to the AS path. In network advertisements from
routers using the local-as command, the router's true AS number (the number specified using the router
bgp as-number command) is prepended to the AS path attribute, and the local AS (the number specified
in the neighbor local-as command) is prepended to the AS path attribute. This makes it appear that the
path to the network is first through the local AS, and then through the true AS. To further illustrate, consider
the following example network.
In this network:
•
Router A is in AS 100.
•
Router B is in AS 300.
•
Router A is an eBGP peer with Router B.
•
Router A's connection to Router B specifies a local-as of 200.
•
Router B is configured to connect to Router A in AS 200.
Therefore:
•
To Router B, all aspects of Router A appear as AS 200.
•
Networks advertised from Router A to Router B will have the AS path 200 100 prepended to the AS path
attribute.
•
Router A will add AS 200 to the AS path of networks learned from Router B.
60000CRG0-35E
Copyright © 2012 ADTRAN, Inc.
BGP Neighbor Command Set
2886
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