Bgp route Aggregation

R1 configuration



router bgp 100
 no synchronization
 bgp log-neighbor-changes
 network 1.1.1.0 mask 255.255.255.0
 neighbor 131.1.12.2 remote-as 200
 no auto-summary


R1#sh ip bgp
BGP table version is 43, local router ID is 1.1.1.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
              r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete

   Network          Next Hop            Metric LocPrf Weight Path
*> 1.1.1.0/24       0.0.0.0                  0         32768 i
*> 2.2.0.0/22       131.1.12.2               0             0 200 i -------route aggregation is done for 2.2.x.x network


R5 configuration


interface Loopback2
 ip address 2.2.0.2 255.255.255.0
!
interface Loopback3
 ip address 2.2.1.2 255.255.255.0
!
interface Loopback4
 ip address 2.2.2.2 255.255.255.0
!
interface Loopback5
 ip address 2.2.3.2 255.255.255.0

router bgp 200
no synchronization
 bgp log-neighbor-changes
 network 2.2.0.0 mask 255.255.255.0
 network 2.2.1.0 mask 255.255.255.0
 network 2.2.2.0 mask 255.255.255.0
 network 2.2.3.0 mask 255.255.255.0
 aggregate-address 2.2.0.0 255.255.252.0 as-set summary-only
 neighbor 131.1.12.1 remote-as 100
 no auto-summary