MPLS L3VPN Konfigurasi OSPF Sham Link

Assalamualikum wr wb

Alhamdulillah kita masih bisa berjumpa kembali tentunya di Belajar IT bersama, melanjutkan materi yang kemarin kali ini akan membahas tentang MPLS L3VPN Konfigurasi OSPF Sham Link, perhatikan topologi berikut ini

Router CE R4 memiliki 2 jalur, yang satunya lewat R1 dan yang satunya lagi lewat R5 (backdoor), karena R5 berada di area yang sama, sedangkan R1 merupakan jalur eksternal, R4 akan lebih memilih ke jalur R5 dibandingkan melewati jalur VPN MPLS yang ada di R1.

Bagaimana mengatasi masalah ini?, untuk mengatasi masalah ini adalah kita buat sebuah jalur Sham-link antara R1 dan R3, agar jalur VPN MPLS lebih diprioritaskan dibandingkan jalur backdoor yang dimiliki oleh R4. oke lanjut ke konfigurasi, pertama kita konfigrasi IP address semua router terlebih dahulu

R1(config)#int lo0
R1(config-if)#ip add 1.1.1.1 255.255.255.255
R1(config-if)#int e0/0
R1(config-if)#ip add 12.12.12.1 255.255.255.0
R1(config-if)#mpls ip
R1(config-if)#no sh
R1(config-if)#ex

R2(config)#int lo0
R2(config-if)#ip add 2.2.2.2 255.255.255.255
R2(config-if)#int e0/0
R2(config-if)#no sh
R2(config-if)#ip add 12.12.12.2 255.255.255.0
R2(config-if)#mpls ip
R2(config-if)#int e0/1
R2(config-if)#no sh
R2(config-if)#ip add 23.23.23.2 255.255.255.0
R2(config-if)#mpls ip
R2(config-if)#ex

R3(config)#int lo0
R3(config-if)#ip add 3.3.3.3 255.255.255.255
R3(config-if)#int e0/0
R3(config-if)#no sh
R3(config-if)#ip add 23.23.23.2 255.255.255.0
R3(config-if)#mpls ip
R3(config-if)#ex

R4(config)#int lo0
R4(config-if)#ip add 4.4.4.4 255.255.255.255
R4(config-if)#int e0/0
R4(config-if)#no sh
R4(config-if)#ip add 10.10.10.2 255.255.255.0
R4(config)#int s2/0
R4(config-if)#ip add 45.45.45.4 255.255.255.0
R4(config-if)#no sh
R4(config-if)#ex

R5(config)#int lo0
R5(config-if)#ip add 5.5.5.5 255.255.255.255
R5(config-if)#int e0/0
R5(config-if)#no sh
R5(config-if)#ip add 20.20.20.2 255.255.255.0
R5(config-if)#int s2/0
R5(config-if)#ip add 45.45.45.5 255.255.255.0
R5(config-if)#no sh
R5(config-if)#ex

Kemudian kita konfigurasi routing eigrp supaya networknya terhubung untuk router P, PE

R1(config)#router eigrp 10
R1(config-router)#no au
R1(config-router)#net 1.1.1.1 0.0.0.0
R1(config-router)#net 12.12.12.0 0.0.0.255
R1(config-router)#ex

R2(config)#router eigrp 10
R2(config-router)#no au
R2(config-router)#net 2.2.2.2 0.0.0.0
R2(config-router)#net 12.12.12.0 0.0.0.255
R2(config-router)#net 23.23.23.0 0.0.0.255
R2(config-router)#

R3(config)#router eigrp 10
R3(config-router)#no au
R3(config-router)#net 3.3.3.3 0.0.0.0
R3(config-router)#net 23.23.23.0 0.0.0.255
R3(config-router)#ex

Kemudian kita buat VRF pada Router PE dan kemudian terapkan pada Interface yang terhubung dengan Router CE.

R1(config)#ip vrf atas
R1(config-vrf)#rd 10:1
R1(config-vrf)#route-target both 10:1
R1(config-vrf)#exi
R1(config)#int e0/1
R1(config-if)#ip vrf forwarding atas
R1(config-if)#ip add 10.10.10.1 255.255.255.0
R1(config-if)#no sh

R3(config)#ip vrf atas
R3(config-vrf)#rd 10:1
R3(config-vrf)#route-target both 10:1
R3(config-vrf)#exi
R3(config)#int e0/1
R3(config-if)#ip vrf forwarding atas
R3(config-if)#ip add 20.20.20.1 255.255.255.0
R3(config-if)#no sh
R3(config-if)#ex

Kemudian kita buat MBGP untuk membentuk jalurnya

R1(config)#router bgp 10
R1(config-router)#no sy
R1(config-router)#nei 3.3.3.3 remote-as 10
R1(config-router)#nei 3.3.3.3 update-source lo0
R1(config-router)#address-family vpnv4
R1(config-router-af)#nei 3.3.3.3 activate
R1(config-router-af)#ex
R1(config-router)#nei 3.3.3.3 remote-as 10
R1(config-router)#address-family ipv4 vrf atas
R1(config-router-af)#redistribute connected
R1(config-router-af)#redistribute vrf atas ospf 10 metric 10
R1(config-router-af)#exi
R1(config-router)#exi

R3(config)#router bgp 10
R3(config-router)#no sy
R3(config-router)#nei 1.1.1.1 remote-as 10
R3(config-router)#nei 1.1.1.1 update-source lo0
R3(config-router)#address-family vpnv4
R3(config-router-af)#nei 1.1.1.1 act
R3(config-router-af)#nei 1.1.1.1 activate
R3(config-router-af)#exi
R3(config-router)#address-family ipv4 vrf atas
R3(config-router-af)#redistribute vrf atas ospf 10 metric 10
R3(config-router-af)#redistribute connected
R3(config-router-af)#ex

Kita aktifkan OSPF agar antar Router CE dan PE dapat saling berkomunikasi.

R1(config-if)#router ospf 10 vrf atas
R1(config-router)#net 10.10.10.0 0.0.0.255 ar 0

R3(config)#router ospf 10 vrf atas
R3(config-router)#net 20.20.20.0 0.0.0.255 ar 0
R3(config-router)#ex

kemudian konfigurasi di router 4 dan 5

R4(config)#router ospf 10
R4(config-router)#net 0.0.0.0 0.0.0.0 ar 0
R4(config-router)#ex

R5(config)#router ospf 10
R5(config-router)#net 0.0.0.0 0.0.0.0 ar 0
R5(config-router)#ex

kemudian kita cek tabel routingnya

R5(config)#do sh ip route
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
       a - application route
       + - replicated route, % - next hop override

Gateway of last resort is not set

      4.0.0.0/32 is subnetted, 1 subnets
O        4.4.4.4 [110/65] via 45.45.45.4, 00:00:16, Serial2/0
      5.0.0.0/32 is subnetted, 1 subnets
C        5.5.5.5 is directly connected, Loopback0
      10.0.0.0/24 is subnetted, 1 subnets
O        10.10.10.0 [110/74] via 45.45.45.4, 00:00:16, Serial2/0
      20.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C        20.20.20.0/24 is directly connected, Ethernet0/0
L        20.20.20.2/32 is directly connected, Ethernet0/0
      45.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C        45.45.45.0/24 is directly connected, Serial2/0
L        45.45.45.5/32 is directly connected, Serial2/0
R5(config)#

Kita buat sebuah jalur sham-link OSPF antara Router PE, agar dipilih menjadi jalur utama meskipun jalur eksternal.

R1(config)#int lo1
R1(config-if)#ip vrf forwarding atas
R1(config-if)#ip add 100.100.100.1 255.255.255.255
R1(config-if)#ex
R1(config)#router ospf 10 vrf atas
R1(config-router)#area 0 sham-link 100.100.100.1 100.100.100.3
R1(config-router)#ex

R3(config)#int lo1
R3(config-if)#ip vrf forwarding atas
R3(config-if)#ip add 100.100.100.3 255.255.255.255
R3(config-if)#exi
R3(config)#router ospf 10 vrf atas
R3(config-router)#area 0 sham-link 100.100.100.3 100.100.100.1
R3(config-router)#ex

Kemudian cek konektifitas Sham-link apakah sudah UP.

R3(config)#do sh ip ospf sham-links
Sham Link OSPF_SL0 to address 100.100.100.1 is up
Area 0 source address 100.100.100.3
Run as demand circuit
DoNotAge LSA allowed. Cost of using 1 State POINT_TO_POINT,
Timer intervals configured, Hello 10, Dead 40, Wait 40,
    Hello due in 00:00:08
    Adjacency State FULL (Hello suppressed)
    Index 1/2/2, retransmission queue length 0, number of retransmission 0
    First 0x0(0)/0x0(0)/0x0(0) Next 0x0(0)/0x0(0)/0x0(0)
    Last retransmission scan length is 0, maximum is 0
    Last retransmission scan time is 0 msec, maximum is 0 msec