BGP sample configuration Case 2-1

Current configuration:
!
version 12.x
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
service udp-small-servers
service tcp-small-servers
!
hostname Router1
!
enable secret 5 Pl$RwwQMKXmRs8oFcaCCvLxX$1$VG/
!
ip subnet-zero
ip name-server x.x.x.x
ip name-server y.y.y.y
!
interface Loopback0
description to Loopback for BGP
ip address 3.3.3.3 255.255.255.255
no ip directed-broadcast
no ip mroute-cache
!
interface Ethernet0
description to Internal network
ip address 10.10.10.1 255.255.255.0
no ip directed-broadcast
no ip mroute-cache
!
interface Serial0
description to ISP A – Line1
ip address 1.1.1.1 255.255.255.252
no ip directed-broadcast
no ip mroute-cache
no fair-queue
!
interface Serial1
description to ISP A – Line2
ip address 2.2.2.1 255.255.255.252
no ip directed-broadcast
no ip mroute-cache
no fair-queue
!
router bgp 100
no auto-summary
neighbor 4.4.4.4 remote-as 200
neighbor 4.4.4.4 version 4
neighbor 4.4.4.4 ebgp-multihop 2
neighbor 4.4.4.4 update-source loopback0
neighbor 4.4.4.4 prefix-list 1 out
!
ip classless
ip route 0.0.0.0 0.0.0.0 Serial0 <—– Default route, if partial routes are receiving from ISP
or you can request ISP to send one thru BGP.
ip route 4.4.4.4 255.255.255.255 Serial0
ip route 4.4.4.4 255.255.255.255 Serial1
!
ip prefix-list 1 description to ISP
ip prefix-list 1 seq 5 permit 10.10.10.0/24 le 32
!
line con 0
line aux 0
line vty 0 4
login
!
end

CCurrent configuration:
!
version 12.x
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
service udp-small-servers
service tcp-small-servers
!
hostname Router2
!
enable secret 5 Pl$RwwQMKXmRs8oFcaCCvLxX$1$VG/
!
ip subnet-zero
ip name-server x.x.x.x
ip name-server y.y.y.y
ip name-server z.z.z.z
!
interface Loopback0
description to Loopback for BGP
ip address 4.4.4.4 255.255.255.255
no ip directed-broadcast
no ip mroute-cache
!
interface POS1/0
description to Uplink
ip address x.x.x.x 255.255.255.252
no ip directed-broadcast
no ip mroute-cache
!
:
:
:
!
interface Serial0
description to customer’s line 1
ip address 1.1.1.2 255.255.255.252
no ip directed-broadcast
no ip mroute-cache
no fair-queue
!
interface Serial1
description to customer’s line 2
ip address 2.2.2.2 255.255.255.252
no ip mroute-cache
no ip directed-broadcast
no fair-queue
!
router bgp 200
no auto-summary
neighbor 3.3.3.3 remote-as 100
neighbor 3.3.3.3 version 4
neighbor 3.3.3.3 ebgp-multihop 2
neighbor 3.3.3.3 update-source loopback0
neighbor 3.3.3.3 default-originate <— If customer request to send a default route
neighbor 3.3.3.3 prefix-list 1 in
!
ip classless
ip route 3.3.3.3 255.255.255.255 Serial0
ip route 3.3.3.3 255.255.255.255 Serial1
!
ip prefix-list 2 description from customer or peer
ip prefix-list 2 seq 5 permit 10.10.10.0/24 le 32
!
!
line con 0
line aux 0
line vty 0 4
login
!
end

Router5#sh ip bgp nei 4.4.4.4 ad
BGP table version is 15, local router ID is 3.3.3.3
Status codes: s suppressed, d damped, h history, * valid, > best, i – internal
Origin codes: i – IGP, e – EGP, ? – incomplete

Network Next Hop Metric LocPrf Weight Path
*> 10.10.10.0/24 0.0.0.0 0 32768 ?
Router5#

Router6#sh ip bgp neighbors 3.3.3.3 ro
BGP table version is 19, local router ID is 4.4.4.4
Status codes: s suppressed, d damped, h history, * valid, > best, i – internal
Origin codes: i – IGP, e – EGP, ? – incomplete

Network Next Hop Metric LocPrf Weight Path
*> 10.10.10.0/24 3.3.3.3 0 0 100 ?

Total number of prefixes 1
Router6#