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DES-7200 Configuration Guide Chapter 6 BGP
Configuration
6-51
the route p to the EBGP neighbor router D. If the router C is configured
asynchronously, it is not necessary for the BGP to wait for the IGP to receive the
route p, so as to send the route p to the EBGP neighbor router D.
6.30.3 Configuring Neighbors to Use aspath Filter
Configure the as-path access-list command for filtering in the configuration
mode firstly. Enter into the route configuration mode of the BGP after
configuration, and use the neighbor filter-list command to apply the configured
as-path access list among the BGP neighbors to filter AS paths.
The detailed configurations are as below:
router bgp 200
neighbor 193.1.12.10 remote-as 100
neighbor 193.1.12.10 filter-list 2 out
neighbor 193.1.12.10 filter-list 3 in
ip as-path access-list 2 permit _200$
ip as-path access-list 2 permit ^100$
ip as-path access-list 3 deny _690$
ip as-path access-list 3 permit .*
This configuration indicates that only the routes permitted by the as-path
access-list 2 can be advertised to the neighbor 193.1.12.10, and the advertised
routes from the neighbor 193.1.12.10 can be received only they are permitted by
the as-path access-list 3.
The following diagram is a configuration eaxmple showing the relationship and IP
addresses of devices:
Do AS path-based filter on Router A.
The following presents the configuraiton of various devices:
Router A configuration:
!
ip as-path access-list 4 deny ^300_
ip as-path access-list 4 permit .*
ip as-path access-list 5 deny ^450_65_
ip as-path access-list 5 permit .*
!
router bgp 100