Information Technology Reference
In-Depth Information
the AS_PATH prepending on R2 over the DS3 to AS 100 is reduced from 2 to 1, and the
BGP session is cleared to allow the new policy to take effect. The use of a BGP soft clear
is the preferred method, preventing prefix flapping.
The result is that more traffic flows over the DS3 from AS 100, with about 25 Mbps from
AS 100 and 22 Mbps over the DS3 from AS 200. The OC-3 link is brought back online, and
traffic flow restabilizes. The traffic flow returns to the prefailure pattern. This policy satis-
fies the enterprise's traffic flow policy requirements. The final configuration for the inbound
policy is shown in Examples 6-9, 6-10, and 6-11.
Inbound Policy Configuration for R1
Example 6-9
R1#show running-config | begin bgp
router bgp 300
no synchronization
bgp log-neighbor-changes
network 172.160.0.0
neighbor 172.160.1.2 remote-as 300
neighbor 172.160.1.2 update-source loopback0
neighbor 172.160.1.3 remote-as 300
neighbor 172.160.1.3 update-source loopback0
neighbor 100.100.100.1 remote-as 100
no auto-summary
!
Example 6-10
Inbound Policy Configuration for R2
R2#show running-config | begin bgp
router bgp 300
no synchronization
bgp log-neighbor-changes
network 172.160.0.0
neighbor 172.160.1.1 remote-as 300
neighbor 172.160.1.1 update-source loopback0
neighbor 172.160.1.3 remote-as 300
neighbor 172.160.1.3 update-source loopback0
neighbor 100.100.150.1 remote-as 100
neighbor 100.100.150.1 route-map AS100_OUT_POLICY out
no auto-summary
!
route-map AS100_OUT_POLICY permit 10
set as-path prepend 300
!
