Information Technology Reference
In-Depth Information
Example 4-24 Sample BGP Configuration on R2 (Continued)
set ip address prefix-list Specific
set community 100:200 no-export
!
route-map AS200-aggregate permit 10
match ip address prefix-list Aggregate
match ip route-source AS200-R4
Example 4-25 shows a similar configuration on R3. Another way to inject the specific
components is to inject both specifics into routers R2 and R3 simultaneously. A preference
can be set for one of the two.
Example 4-25 Sample BGP Configuration on R3
router bgp 100
bgp inject-map AS200-specific exist-map AS200-aggregate
neighbor 192.168.13.1 remote-as 100
neighbor 192.168.13.1 send-community
neighbor 192.168.23.2 remote-as 100
neighbor 192.168.23.2 send-community
neighbor 192.168.35.5 remote-as 200
!
ip bgp-community new-format
ip prefix-list AS200-R5 seq 5 permit 192.168.35.5/32
ip prefix-list Aggregate seq 5 permit 172.16.0.0/16
ip prefix-list Specific seq 5 permit 172.16.2.0/24
!
route-map AS200-specific permit 10
set ip address prefix-list Specific
set community 100:200 no-export
!
route-map AS200-aggregate permit 10
match ip address prefix-list Aggregate
match ip route-source AS200-R5
Example 4-26 shows the BGP RIB on R1. Note that the BGP next hops are border routers
that announce the aggregate and not the routers that inject the specifics. With the more-
specific information, R1 directs traffic to R4 for 172.16.1.0 and to R5 for 172.16.2.0. The
aggregate is used for all other traffic to 172.16.0.0.
Example 4-26 BGP RIB on R1
R1#show ip bgp
BGP table version is 38, local router ID is 192.168.14.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure
Origin codes: i - IGP, e - EGP, ? - incomplete
continues
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