! Listing 8.27: Single router providing multihoming via BGP
!
!Copyright (C) 2001 by Vincent C Jones. All Rights Reserved.


version 11.0
!
hostname External
!
ip subnet-zero
!
interface FastEthernet0/0
 description No Man's Land LAN #1
 ip address 100.0.0.33 255.255.255.224
 ip access-group 193 in
 no ip directed-broadcast
!
interface FastEthernet0/1
 description No Man's Land LAN #2
 ip address 101.0.0.33 255.255.255.224
 ip access-group 194 in
 no ip directed-broadcast
!
interface Serial1/0
 no ip address
 encapsulation frame-relay IETF
!
interface Serial1/0.1 point-to-point
 description Link to the ISP providing 100.0.0.0/24
 ip address 110.0.0.1 255.255.255.252
 ip access-group 191 in
 ip access-group 192 out
 no ip unreachables
 no ip directed-broadcast
 no arp frame-relay
 frame-relay interface-dlci 500 IETF
 bandwidth 1500
!
interface Serial2/0
 description Link to the ISP providing 101.0.0.0/24
 ip address 120.0.0.1 255.255.255.252
 ip access-group 195 in
 ip access-group 196 out
 no ip unreachables
 no ip directed-broadcast
 bandwidth 1500
!
router bgp 60000
 network 100.0.0.0 mask 255.255.255.0
 network 101.0.0.0 mask 255.255.255.0
 aggregate-address 110.0.0.0 255.255.255.252 summary-only
 aggregate-address 120.0.0.0 255.255.255.252 summary-only
 redistribute connected
 neighbor 110.0.0.2 remote-as 54321
 neighbor 110.0.0.2 version 4
 neighbor 110.0.0.2 filter-list 10 out
 neighbor 120.0.0.2 remote-as 55555
 neighbor 120.0.0.2 version 4
 neighbor 120.0.0.2 filter-list 10 out
 no auto-summary
!
ip classless
ip route 0.0.0.0 0.0.0.0 Serial2/0
ip route 0.0.0.0 0.0.0.0 Serial1/0.1 200
ip route 100.0.0.0 255.255.255.0 Null0
ip route 100.0.0.8 255.255.255.248 100.0.0.46
ip route 100.0.0.16 255.255.255.240 100.0.0.46
ip route 100.0.0.64 255.255.255.192 100.0.0.46
ip route 101.0.0.0 255.255.255.0 Null0
ip route 101.0.0.8 255.255.255.248 101.0.0.46
ip route 101.0.0.16 255.255.255.240 101.0.0.46
ip route 101.0.0.64 255.255.255.192 101.0.0.46
ip as-path access-list 10 permit ^(_60000)*$
!
end