CCIE Bootcamp: MPLS

Hari ke-5 saya akan menulis mengenai MPLS dasar mulai dari OSPF, LDP, BGP, MP-BGP dan PE-CE routing menggunakan RIP dan EIGRP. Mari kita mulai dari konfigurasi alamat IP.

Konfigurasi PE1:

interface Loopback0
 ip address 10.10.10.1 255.255.255.255
!
interface FastEthernet0/0
 ip address 192.168.10.1 255.255.255.252
!
router ospf 1
 log-adjacency-changes
 network 10.10.10.1 0.0.0.0 area 0
 network 192.168.10.1 0.0.0.0 area 0

 

Konfigurasi P:

interface Loopback0
 ip address 10.10.10.10 255.255.255.255
!
interface FastEthernet0/0
 ip address 192.168.10.2 255.255.255.252
!
interface FastEthernet0/1
 ip address 192.168.20.1 255.255.255.252
!
router ospf 1
 network 10.10.10.10 0.0.0.0 area 0
 network 192.168.10.2 0.0.0.0 area 0
 network 192.168.20.1 0.0.0.0 area 0

 

Konfigurasi PE2:

interface Loopback0
 ip address 10.10.10.2 255.255.255.252
!
interface FastEthernet0/0
 ip address 192.168.20.2 255.255.255.252
!
router ospf 1
 network 10.10.10.2 0.0.0.0 area 0
 network 192.168.20.2 0.0.0.0 area 0

 

Konfigurasi di CE-A1:

interface Loopback0
 ip address 10.0.0.1 255.255.255.255
!
interface Serial0/0
 ip address 192.168.0.2 255.255.255.252

 

Konfigurasi di CE-A2

interface Loopback0
 ip address 10.0.0.2 255.255.255.255
!
interface Serial0/0
 ip address 192.168.0.6 255.255.255.252

 

Konfigurasi di CE-B1

interface Loopback0
 ip address 10.0.0.1 255.255.255.255
!
interface Serial0/0
 ip address 192.168.0.2 255.255.255.252

 

Konfigurasi di CE-B2

interface Loopback0
 ip address 10.0.0.2 255.255.255.255
!
interface Serial0/0
 ip address 192.168.0.6 255.255.255.252

 

Setelah konfigurasi dasar IP dan OSPF selesai kita lanjut dengan menjalankan Label Distribution Protocol (LDP).

Konfigurasi PE1:

mpls ldp router-id Loopback0
!
mpls ip
!
interface FastEthernet0/0
 mpls ip

 

Konfigurasi P:

mpls ldp router-id Loopback0
!
mpls ip
!
interface FastEthernet0/0
 mpls ip
!
interface FastEthernet0/1
 mpls ip

 

Konfigurasi PE2:

mpls ldp router-id Loopback0
!
mpls ip
!
interface FastEthernet0/0
 mpls ip

 

Kita bisa mengecek status neighbor LDP dengan perintah show mpls ldp neighbor.

PE1#sh mpls ldp neighbor
 Peer LDP Ident: 10.10.10.10:0; Local LDP Ident 10.10.10.1:0
 TCP connection: 10.10.10.10.25695 - 10.10.10.1.646
 State: Oper; Msgs sent/rcvd: 8/8; Downstream
 Up time: 00:00:20
 LDP discovery sources:
 FastEthernet0/0, Src IP addr: 192.168.10.2
 Addresses bound to peer LDP Ident:
 192.168.10.2 10.10.10.10 192.168.20.1
P#sh mpls ldp neighbor
 Peer LDP Ident: 10.10.10.1:0; Local LDP Ident 10.10.10.10:0
 TCP connection: 10.10.10.1.646 - 10.10.10.10.25695
 State: Oper; Msgs sent/rcvd: 8/9; Downstream
 Up time: 00:00:54
 LDP discovery sources:
 FastEthernet0/0, Src IP addr: 192.168.10.1
 Addresses bound to peer LDP Ident:
 192.168.10.1 10.10.10.1
 Peer LDP Ident: 10.10.10.2:0; Local LDP Ident 10.10.10.10:0
 TCP connection: 10.10.10.2.646 - 10.10.10.10.25231
 State: Oper; Msgs sent/rcvd: 9/9; Downstream
 Up time: 00:00:54
 LDP discovery sources:
 FastEthernet0/1, Src IP addr: 192.168.20.2
 Addresses bound to peer LDP Ident:
 192.168.20.2 10.10.10.2
PE2#sh mpls ldp neighbor
 Peer LDP Ident: 10.10.10.10:0; Local LDP Ident 10.10.10.2:0
 TCP connection: 10.10.10.10.25231 - 10.10.10.2.646
 State: Oper; Msgs sent/rcvd: 9/9; Downstream
 Up time: 00:01:06
 LDP discovery sources:
 FastEthernet0/0, Src IP addr: 192.168.20.1
 Addresses bound to peer LDP Ident:
 192.168.10.2 10.10.10.10 192.168.20.1

 

Sampai di sini tidak ada penambahan konfigurasi untuk router P. Sekarang mari kita konfigurasi VRF untuk site A dan B.

Di PE1:

ip vrf B1
 rd 65000:2
 route-target export 65000:2
 route-target import 65000:2

 

Di PE2:

ip vrf A2
 rd 65000:1
 route-target export 65000:1
 route-target import 65000:1
!
ip vrf B2
 rd 65000:2
 route-target export 65000:2
 route-target import 65000:2

 

Setelah itu kita konfigurasi BGP dan MP-BGP.

BGP di PE1:

router bgp 65000
 neighbor 10.10.10.2 remote-as 65000
 neighbor 10.10.10.2 update-source Loopback0

 

MP-BGP di PE1:

router bgp 65000
 !
 address-family vpnv4
 neighbor 10.10.10.2 activate
 neighbor 10.10.10.2 send-community extended

 

BGP di PE2:

router bgp 65000
 neighbor 10.10.10.1 remote-as 65000
 neighbor 10.10.10.1 update-source Loopback0

 

MP-BGP di PE1:

router bgp 65000
 !
 address-family vpnv4
 neighbor 10.10.10.1 activate
 neighbor 10.10.10.1 send-community extended

 

Mari kita cek status neighbor untuk BGP dan MP-BGP.

BGP

PE1#sh ip bgp summary
BGP router identifier 10.10.10.1, local AS number 65000
BGP table version is 1, main routing table version 1
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
10.10.10.2 4 65000 19 19 1 0 0 00:14:25 0
PE2#sh ip bgp summary
BGP router identifier 10.10.10.2, local AS number 65000
BGP table version is 1, main routing table version 1
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
10.10.10.1 4 65000 19 19 1 0 0 00:14:41 0

 

MP-BGP

PE1#sh ip bgp vpnv4 all summary
BGP router identifier 10.10.10.1, local AS number 65000
BGP table version is 9, main routing table version 9
4 network entries using 560 bytes of memory
4 path entries using 272 bytes of memory
3/2 BGP path/bestpath attribute entries using 372 bytes of memory
1 BGP extended community entries using 24 bytes of memory
0 BGP route-map cache entries using 0 bytes of memory
0 BGP filter-list cache entries using 0 bytes of memory
Bitfield cache entries: current 1 (at peak 1) using 32 bytes of memory
BGP using 1260 total bytes of memory
BGP activity 4/0 prefixes, 4/0 paths, scan interval 15 secs
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
10.10.10.2 4 65000 20 20 9 0 0 00:15:05 2
PE2#sh ip bgp vpnv4 all summary
BGP router identifier 10.10.10.2, local AS number 65000
BGP table version is 9, main routing table version 9
4 network entries using 560 bytes of memory
4 path entries using 272 bytes of memory
3/2 BGP path/bestpath attribute entries using 372 bytes of memory
1 BGP extended community entries using 24 bytes of memory
0 BGP route-map cache entries using 0 bytes of memory
0 BGP filter-list cache entries using 0 bytes of memory
Bitfield cache entries: current 1 (at peak 1) using 32 bytes of memory
BGP using 1260 total bytes of memory
BGP activity 4/0 prefixes, 4/0 paths, scan interval 15 secs
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
10.10.10.1 4 65000 20 20 9 0 0 00:15:33 2

 

Sampai di sini kita sudah siap untuk menambahkan customer A dan B ke dalam MPLS. Pertama kita akan menambahkan customer A dengan menggunakan routing protocol RIP.

Konfigurasi di PE1:

ip vrf A1
 rd 65000:1
 route-target export 65000:1
 route-target import 65000:1
!
interface Serial0/0
 ip vrf forwarding A1
 ip address 192.168.0.1 255.255.255.252
!
router rip
 version 2
 !
 address-family ipv4 vrf A1
 redistribute bgp 65000 metric transparent
 network 192.168.0.0
 no auto-summary
 version 2
!
router bgp 65000
 !
 address-family ipv4 vrf A1
 redistribute rip

 

Konfigurasi di PE2:

ip vrf A2
 rd 65000:1
 route-target export 65000:1
 route-target import 65000:1
!
interface Serial0/0
 ip vrf forwarding A2
 ip address 192.168.0.5 255.255.255.252
!
router rip
 version 2
 !
 address-family ipv4 vrf A2
 redistribute bgp 65000 metric transparent
 network 192.168.0.0
 no auto-summary
 version 2
!
router bgp 65000
 !
 address-family ipv4 vrf A2
 redistribute rip

 

Konfigurasi di CE-A1

router rip
 version 2
 network 0.0.0.0
 no auto-summary

 

Konfigurasi di CE-A2

router rip
 version 2
 network 0.0.0.0
 no auto-summary

 

Mari kita cek tabel routing di CE-A1 dan CE-A2.

CE-A1#sh ip route rip
 10.0.0.0/32 is subnetted, 2 subnets
R 10.0.0.2 [120/2] via 192.168.0.1, 00:00:15, Serial0/0
 192.168.0.0/30 is subnetted, 2 subnets
R 192.168.0.4 [120/1] via 192.168.0.1, 00:00:15, Serial0/0
CE-A1#ping 10.0.0.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.0.0.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 8/16/24 ms
CE-A2#sh ip route rip
 10.0.0.0/32 is subnetted, 2 subnets
R 10.0.0.1 [120/2] via 192.168.0.5, 00:00:25, Serial0/0
 192.168.0.0/30 is subnetted, 2 subnets
R 192.168.0.0 [120/1] via 192.168.0.5, 00:00:25, Serial0/0
CE-A2#ping 10.0.0.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.0.0.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 8/11/16 ms

 

Selanjutnya kita akan menambahkan customer B dengan routing protocol EIGRP

Konfigurasi di PE1:

ip vrf B1
 rd 65000:2
 route-target export 65000:2
 route-target import 65000:2
!
interface Serial0/1
 ip vrf forwarding B1
 ip address 192.168.0.1 255.255.255.252
!
router eigrp 65000
 !
 address-family ipv4 vrf B1
 redistribute bgp 65000 metric 1 1 1 1 1
 network 192.168.0.0
 no auto-summary
 autonomous-system 100
!
router bgp 65000
 !
 address-family ipv4 vrf B1
 redistribute eigrp 100

 

Konfigurasi di PE2:

ip vrf B2
 rd 65000:2
 route-target export 65000:2
 route-target import 65000:2
!
interface Serial0/1
 ip vrf forwarding B2
 ip address 192.168.0.1 255.255.255.252
!
router eigrp 65000
 !
 address-family ipv4 vrf B2
 redistribute bgp 65000 metric 1 1 1 1 1
 network 192.168.0.0
 no auto-summary
 autonomous-system 100
!
router bgp 65000
 !
 address-family ipv4 vrf B2
 redistribute eigrp 100

 

Konfigurasi di CE-B1

router eigrp 100
 network 10.0.0.0
 network 192.168.0.0
 no auto-summary

 

Konfigurasi di CE-B2

router eigrp 100
 network 10.0.0.0
 network 192.168.0.0
 no auto-summary

 

Kita cek lagi tabel routing di CE-B1 dan CE-B2.

CE-B1#sh ip route eigrp
 10.0.0.0/32 is subnetted, 2 subnets
D 10.0.0.2 [90/2809856] via 192.168.0.1, 00:06:56, Serial0/0
 192.168.0.0/30 is subnetted, 2 subnets
D 192.168.0.4 [90/2681856] via 192.168.0.1, 00:06:56, Serial0/0
CE-B1#ping 10.0.0.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.0.0.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 8/12/16 ms
CE-B2#sh ip route eigrp
 10.0.0.0/32 is subnetted, 2 subnets
D 10.0.0.1 [90/2809856] via 192.168.0.5, 00:07:38, Serial0/0
 192.168.0.0/30 is subnetted, 2 subnets
D 192.168.0.0 [90/2681856] via 192.168.0.5, 00:07:38, Serial0/0
CE-B2#ping 10.0.0.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.0.0.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 12/13/16 ms

 

Sekarang mari kita menambahkan multicast di B1 dan B2. Kita konfigurasi multicast dengan static RP melewati tunnel GRE.

Konfigurasi B1:

ip multicast-routing
!
interface Loopback0
 ip pim sparse-mode
 ip igmp join-group 239.0.0.1
!
interface Tunnel1
 ip address 12.12.12.1 255.255.255.252
 ip pim sparse-mode
 tunnel source Loopback0
 tunnel destination 10.0.0.2
!
ip pim rp-address 10.0.0.1

 

Konfigurasi B2:

ip multicast-routing
!
interface Loopback0
 ip pim sparse-mode
!
interface Tunnel1
 ip address 12.12.12.2 255.255.255.252
 ip pim sparse-mode
 tunnel source Loopback0
 tunnel destination 10.0.0.1
!
ip pim rp-address 10.0.0.1

 

Mari kita ping IP multicast 239.0.0.1 dari B2

CE-B2#ping 239.0.0.1
Type escape sequence to abort.
Sending 1, 100-byte ICMP Echos to 239.0.0.1, timeout is 2 seconds:
Reply to request 0 from 12.12.12.1, 16 ms

 

Mari kita lihat juga informasi tentang RP di B2.

CE-B2#sh ip mroute
 IP Multicast Routing Table
 Flags: D - Dense, S - Sparse, B - Bidir Group, s - SSM Group, C - Connected,
 L - Local, P - Pruned, R - RP-bit set, F - Register flag,
 T - SPT-bit set, J - Join SPT, M - MSDP created entry,
 X - Proxy Join Timer Running, A - Candidate for MSDP Advertisement,
 U - URD, I - Received Source Specific Host Report,
 Z - Multicast Tunnel, z - MDT-data group sender,
 Y - Joined MDT-data group, y - Sending to MDT-data group
 Outgoing interface flags: H - Hardware switched, A - Assert winner
 Timers: Uptime/Expires
 Interface state: Interface, Next-Hop or VCD, State/Mode
(*, 239.0.0.1), 00:10:07/stopped, RP 10.0.0.1, flags: SPF
 Incoming interface: Null, RPF nbr 0.0.0.0
 Outgoing interface list: Null
(12.12.12.2, 239.0.0.1), 00:03:36/00:02:26, flags: PFT
 Incoming interface: Tunnel1, RPF nbr 0.0.0.0, Registering
 Outgoing interface list: Null
(*, 224.0.1.40), 00:11:37/00:02:35, RP 10.0.0.1, flags: SJCL
 Incoming interface: Null, RPF nbr 0.0.0.0
 Outgoing interface list:
 Loopback0, Forward/Sparse, 00:11:37/00:02:35
 CE-B2#sh ip pim rp mapping
 PIM Group-to-RP Mappings
Group(s): 224.0.0.0/4, Static
 RP: 10.0.0.1 (?)

CCIE Bootcamp: BGP

Hari ke-5 saya menulis mengenai BGP attributes dan bagaimana mengubah jalur menggunakan atribut ini. Atribut yang akan diubah adalah Weight (Cisco proprietary), Local Preference dan AS-Path. Kita lihat topologi dan konfigurasi berikut.

Konfigurasi R1:

interface Loopback0
 ip address 1.1.1.1 255.255.255.255
!
interface FastEthernet0/0
 ip address 12.12.12.1 255.255.255.0
!
interface FastEthernet0/1
 ip address 13.13.13.1 255.255.255.0
!
router bgp 1
 network 1.1.1.1 mask 255.255.255.255
 neighbor 12.12.12.2 remote-as 2
 neighbor 13.13.13.3 remote-as 3

 

Konfigurasi R2:

interface FastEthernet0/0
 ip address 12.12.12.2 255.255.255.0
!
interface FastEthernet0/1
 ip address 23.23.23.2 255.255.255.0
!
router bgp 2
 neighbor 12.12.12.1 remote-as 1
 neighbor 23.23.23.3 remote-as 3

 

Konfigurasi R3:

interface Loopback0
 ip address 3.3.3.3 255.255.255.255
!
interface Loopback1
 ip address 10.0.0.1 255.255.255.255
!
interface Loopback2
 ip address 10.0.0.2 255.255.255.255
!
interface Loopback3
 ip address 10.0.0.3 255.255.255.255
!
interface FastEthernet0/0
 ip address 13.13.13.3 255.255.255.0
!
interface FastEthernet0/1
 ip address 23.23.23.3 255.255.255.0
!
router bgp 3
 network 10.0.0.1 mask 255.255.255.255
 network 10.0.0.2 mask 255.255.255.255
 network 10.0.0.3 mask 255.255.255.255
 neighbor 13.13.13.1 remote-as 1
 neighbor 23.23.23.2 remote-as 2

 

Mari kita lihat tabel BGP di R1.

R1#sh ip bgp
BGP table version is 7, 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
*> 1.1.1.1/32 0.0.0.0 0 32768 i
* 10.0.0.1/32 12.12.12.2 0 2 3 i
*> 13.13.13.3 0 0 3 i
* 10.0.0.2/32 12.12.12.2 0 2 3 i
*> 13.13.13.3 0 0 3 i
* 10.0.0.3/32 12.12.12.2 0 2 3 i
*> 13.13.13.3 0 0 3 i

 

Jalur ke loopback R3 akan langsung lewat R3, kita akan mengubah ke R2 terlebih dahulu.
 

1. Weight
Nilai awal Weight adalah 0, BGP akan memilih jalur yang memiliki nilai yang lebih tinggi. Weight ini hanya berlaku untuk router itu sendiri. Kita akan membuat jalur ke 10.0.0.1 melewati R2.

R1(config)#access-list 1 permit 10.0.0.1
R1(config)#route-map PATH-SELECT permit 10
R1(config-route-map)#match ip address 1
R1(config-route-map)#set weight 100

 

Route-map ini akan dipasang di BGP neighbor R2 ke arah masuk (in). Path menuju 10.10.10.1 datang dari R2 dan R3 menuju R1, supaya R1 lebih memilih jalur R2 maka harus diubah atributnya dari arah R2 ke R1 di R1.

R1(config)#router bgp 1
R1(config-router)#neighbor 12.12.12.2 route-map PATH-SELECT in
R1(config-router)#end
R1#clear ip bgp * soft

 

Perintah clear ip bgp * soft adalah untuk soft reload koneksi BGP ke semua neighbor, mari kita lihat tabel BGP-nya.

R1#sh ip bgp
BGP table version is 8, 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
*> 1.1.1.1/32 0.0.0.0 0 32768 i
*> 10.0.0.1/32 12.12.12.2 100 2 3 i
* 13.13.13.3 0 0 3 i
*> 10.0.0.2/32 13.13.13.3 0 0 3 i
*> 10.0.0.3/32 13.13.13.3 0 0 3 i

 

Ok jalur ke 10.0.0.1 sudah melalui R2 tapi coba lihat jalur selain 10.0.0.1 tidak ada lagi yang lewat R2. Ini terjadi karena pada dasarnya route-map mempunyai implicit deny, yaitu pada akhir sequence semua akan di-deny. Sekarang mari kita tambahkan permit di akhir route-map.

R1(config)#route-map PATH-SELECT permit 100
R1(config-route-map)#do clear ip bgp * soft
R1(config-route-map)#do sh ip bgp
BGP table version is 8, 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
*> 1.1.1.1/32 0.0.0.0 0 32768 i
*> 10.0.0.1/32 12.12.12.2 100 2 3 i
* 13.13.13.3 0 0 3 i
* 10.0.0.2/32 12.12.12.2 0 2 3 i
*> 13.13.13.3 0 0 3 i
* 10.0.0.3/32 12.12.12.2 0 2 3 i
*> 13.13.13.3 0 0 3 i

 

Sekarang sudah ok semua.

2. Local Preference
Nilai awal Local Preference adalah 100, BGP akan memilih jalur yang memiliki nilai yang lebih tinggi. Local Preference ini hanya berlaku untuk AS itu sendiri. Kita akan membuat jalur ke 10.10.10.2 melewati R2.

R1(config)#route-map PATH-SELECT permit 20
R1(config-route-map)#match ip address 2
R1(config-route-map)#set local-preference 200
R1(config-route-map)#do clear ip bgp * soft
R1(config-route-map)#do sh ip bgp
BGP table version is 9, 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
*> 1.1.1.1/32 0.0.0.0 0 32768 i
*> 10.0.0.1/32 12.12.12.2 100 2 3 i
* 13.13.13.3 0 0 3 i
*> 10.0.0.2/32 12.12.12.2 200 0 2 3 i
* 13.13.13.3 0 0 3 i
* 10.0.0.3/32 12.12.12.2 0 2 3 i
*> 13.13.13.3 0 0 3 i

 

Ok, jalur ke 10.10.10.2 sudah lewat R2. Kita tidak perlu menambahkan route-map ke neighbor di BGP karena kita memakai route-map yang sama.

 

3. AS-Path
BGP akan memilih AS-path yang lebih pendek. Kita bisa mengubah AS-path dari R3 menjadi lebih panjang sehingga BGP lebih memilih R2. Pengubahan AS-path ini dilakukan di R3 ke arah R1 dengan route-map ke arah luar (out).

R3(config)#access-list 3 permit 10.0.0.3
R3(config)#route-map PATH-SELECT permit 30
R3(config-route-map)#match ip address 3
R3(config-route-map)#set as-path prepend 3 3 3
R3(config-route-map)#route-map PATH-SELECT permit 100
R3(config-route-map)#router bgp 3
R3(config-router)#nei 13.13.13.1 route-map PATH-SELECT out
R3(config-router)#do clear ip bgp * soft
R1#sh ip bgp
BGP table version is 10, 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
*> 1.1.1.1/32 0.0.0.0 0 32768 i
*> 10.0.0.1/32 12.12.12.2 100 2 3 i
* 13.13.13.3 0 0 3 i
*> 10.0.0.2/32 12.12.12.2 200 0 2 3 i
* 13.13.13.3 0 0 3 i
*> 10.0.0.3/32 12.12.12.2 0 2 3 i
* 13.13.13.3 0 0 3 3 3 3 i

 

Jalur ke 10.0.0.3 lewat R3 akan melewati 4 AS sedangkan melewati R2 hanya 2 AS, BGP akan memilih jalur lewat R2.