Kali ini saya akan melanjutkan konfigurasi LAB di Cisco Packet Tracert Selanjutnya Yaitu Lab OSPF
Tujuan
Setting OSPF
Setting router-id OSPF
Setting passive-interface dan network type loopback OSPF
Konsep Dasar
OSPF singkatan dari Open Shortest Path First
OSPF merupakan routing protocol open standar yang diimplementasikan oleh berbagai
macam vendor, termasuk Cisco
Link-state protocol
OSPF bekerja dengan menggunakan algoritma Dijkstra
Hop count unlimited
Metric: cost (cost=10^8 / BW)
Administrative Distance: 110
Classless routing protocol
Mendukung VLSM dan CIDR
Hanya mendukung equal cost load balancing
Terdapat konsep area untuk memudahkan manajemen dan control traffic
Menyediakan design hierarki dengan multiple area
Harus memiliki satu area yang disebut sebagai area 0 atau backbone area
Semua area selain 0 (non-backbone area) harus terhubung ke area 0
Dari scalabilitas lebih baik dibandingkan dengan protocol distance vector
Mendukung autentikasi
Update melalui multicast address: 224.0.0.5
Konvergensi cepat
Mengirimkan hello packet setiap 10 second
Trigger/Incrementeal updates
o Router mengirimkan update hanya jika terjadi perubahan dan tidak mengirimkan
semua routing table pada periodic update
OSPF memaintain tiga tabel
1. Neighbor table
- Dikenal juga sebagai adjacency database
- Menampilkan informasi directly connected router (neighbors)
- Command: show ip ospf neighbor
2. Database table
- Disebut juga sebagai LSDB (link state database)
- Menampilkan semua kemungkinan informasi route menuju network dalam satu area
- Command: show ip ospf database
3. Routing table
- Menampilkan best route menuju network destination
- Command: show ip route
Dua step menggunakan routing protocol dinamis secara umum:
1. Pilih routing protocol
2. Advertise directly connected network (jaringan yang terhubung langsung dengan router)
Konfigurasi OSPF
Router(config)# router ospf <process-id>
Router(config-router)# network <network-id> <wildcard-mask> area <area-id>
Router(config-router)# network <network-id> <wildcard-mask> area <area-id>
network <Network-ID> : untuk advertise network yang terhubung langsung dengan router
(directly connected network).
wildcard-mask
wildcard-mask : inverse subnet-mask
Keuntungan OSPF
Open standard
Tidak ada batasan jumlah hop
Loop free
Konvergensi lebih cepat
Kerugian OSPF
Mengkonsumsi lebih banyak resource CPU
Kompleks dalam hal design dan implementasi
Hanya mendukung equal load balancing
Hanya mendukung protocol IP
Konfigurasi
Login console ke R1 atau R2 untuk mempraktikkan Lab 8-OSPF.
Tampilkan routing table sebelum disetting OSPF di R1
R1#sh ip route
Codes: C - connected, S - static, I - IGRP, 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, E - EGP
i - IS-IS, 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
Gateway of last resort is not set
12.0.0.0/24 is subnetted, 1 subnets
C 12.12.12.0 is directly connected, FastEthernet1/0
172.16.0.0/24 is subnetted, 2 subnets
C 172.16.1.0 is directly connected, Loopback1
C 172.16.2.0 is directly connected, Loopback2
C 192.168.1.0/24 is directly connected, FastEthernet0/0
R1#
Dari output diatas, hanya terdapat directly connected network yang ditandai dengan kode C.
Tampilkan routing table sebelum disetting OSPF di R2
R2#show ip route
Codes: C - connected, S - static, I - IGRP, 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, E - EGP
i - IS-IS, 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
Gateway of last resort is not set
12.0.0.0/24 is subnetted, 1 subnets
C 12.12.12.0 is directly connected, FastEthernet1/0
172.16.0.0/24 is subnetted, 2 subnets
C 172.16.3.0 is directly connected, Loopback0
C 172.16.4.0 is directly connected, Loopback1
C 192.168.2.0/24 is directly connected, FastEthernet0/0
R2#
Agar proses routing berhasil, harus disetting OSPF disemua router terlebih dulu. Setelah itu baru
diverifikasi dengan tes Ping end-to-end device-nya.
Setting OSPF di R1
Command untuk mensetting OSPF.
R1(config)#router ospf 1
R1(config-router)#network 12.12.12.0 0.0.0.255 area 0
R1(config-router)#network 172.16.1.0 0.0.0.255 area 0
R1(config-router)#network 172.16.2.0 0.0.0.255 area 0
R1(config-router)#network 192.168.1.0 0.0.0.255 area 0
R1(config-router)#
Setting OSPF di R2
Command untuk mensetting OSPF.
R2(config)#router ospf 1
R2(config-router)#network 12.12.12.0 0.0.0.255 area 0
R2(config-router)#network 172.16.3.0 0.0.0.255 area 0
R2(config-router)#network 172.16.4.0 0.0.0.255 area 0
R2(config-router)#network 192.168.2.0 0.0.0.255 area 0
Verifikasi
Tampilkan routing table setelah disetting OSPF di R1
R1#show ip route
Codes: C - connected, S - static, I - IGRP, 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, E - EGP
i - IS-IS, 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
Gateway of last resort is not set
12.0.0.0/24 is subnetted, 1 subnets
C 12.12.12.0 is directly connected, FastEthernet1/0
172.16.0.0/16 is variably subnetted, 4 subnets, 2 masks
C 172.16.1.0/24 is directly connected, Loopback1
C 172.16.2.0/24 is directly connected, Loopback2
O 172.16.3.3/32 [110/2] via 12.12.12.2, 00:01:31, FastEthernet1/0
O 172.16.4.4/32 [110/2] via 12.12.12.2, 00:01:31, FastEthernet1/0
C 192.168.1.0/24 is directly connected, FastEthernet0/0
O 192.168.2.0/24 [110/2] via 12.12.12.2, 00:00:40, FastEthernet1/0
R1#
Tampilkan routing table setelah disetting OSPF di R2
R2#show ip route
Codes: C - connected, S - static, I - IGRP, 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, E - EGP
i - IS-IS, 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
Gateway of last resort is not set
12.0.0.0/24 is subnetted, 1 subnets
C 12.12.12.0 is directly connected, FastEthernet1/0
172.16.0.0/16 is variably subnetted, 4 subnets, 2 masks
O 172.16.1.1/32 [110/2] via 12.12.12.1, 00:02:07, FastEthernet1/0
O 172.16.2.2/32 [110/2] via 12.12.12.1, 00:02:07, FastEthernet1/0
C 172.16.3.0/24 is directly connected, Loopback0
C 172.16.4.0/24 is directly connected, Loopback1
O 192.168.1.0/24 [110/2] via 12.12.12.1, 00:02:07, FastEthernet1/0
C 192.168.2.0/24 is directly connected, FastEthernet0/0
Tampilkan informasi neighbor OSPF di R1
R1#show ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
172.16.4.4 1 FULL/DROTHER 00:00:35 12.12.12.2 FastEthernet1/0
R1#
Tampilkan informasi neighbor OSPF di R2
R2#show ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
172.16.2.2 1 FULL/DR 00:00:31 12.12.12.1 FastEthernet1/0
R2#
Tampilkan informasi routing protocol di R1
R1#show ip protocol
Routing Protocol is "ospf 1"
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Router ID 172.16.2.2
Number of areas in this router is 1. 1 normal 0 stub 0 nssa
Maximum path: 4
Routing for Networks:
12.12.12.0 0.0.0.255 area 0
172.16.1.0 0.0.0.255 area 0
172.16.2.0 0.0.0.255 area 0
192.168.1.0 0.0.0.255 area 0
Routing Information Sources:
Gateway Distance Last Update
172.16.2.2 110 00:07:22
172.16.4.4 110 00:06:07
Distance: (default is 110)
R1#
Dari informasi routing diatas, R1 menjalankan OSPF dengan proses ID 1. Ada 4 network yang
diroutingkan oleh R1. Administrative distance 110. R1 memiliki router ID 172.16.2.2.
R1 memiliki neighbor 172.16.4.4 (IP Loopback R2). 172.16.4.4 merupakan router-ID R2.
Note: ulangi langkah yang sama diatas untuk menampilkan informasi neighbor dan
informasi routing protocol di R2
Tampilkan informasi database OSPF di R1
R1#show ip ospf database
OSPF Router with ID (172.16.2.2) (Process ID 1)
Router Link States (Area 0)
Link ID ADV Router Age Seq# Checksum Link count
172.16.2.2 172.16.2.2 472 0x80000005 0x00e483 4
172.16.4.4 172.16.4.4 397 0x80000004 0x00ba9c 4
Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
12.12.12.1 172.16.2.2 472 0x80000001 0x00720b
R1#
Di area 0 hanya terdapat 2 router dengan ID : 172.16.2.2 dan 172.16.4.4.
Tes Ping dari Laptop1 ke Laptop2
Laptop1>ping 192.168.2.1
Pinging 192.168.2.1 with 32 bytes of data:
Reply from 192.168.2.1: bytes=32 time=1ms TTL=126
Reply from 192.168.2.1: bytes=32 time=1ms TTL=126
Reply from 192.168.2.1: bytes=32 time=0ms TTL=126
Reply from 192.168.2.1: bytes=32 time=0ms TTL=126
Ping statistics for 192.168.2.1:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 0ms, Maximum = 1ms, Average = 0ms
Ping dari Laptop1 ke Laptop2 berhasil.
Traceroute dari Laptop1 ke Laptop2
Laptop1>tracert 192.168.2.1
Tracing route to 192.168.2.1 over a maximum of 30 hops:
1 1 ms 0 ms 0 ms 192.168.1.254
2 0 ms 0 ms 0 ms 12.12.12.2
3 0 ms 0 ms 0 ms 192.168.2.1
Trace complete.
Untuk menuju Laptop2 dari Laptop1 membutuhkan 3 hop.
Tes Ping dari Laptop2 ke Laptop1
Laptop2>ping 192.168.1.1
Pinging 192.168.1.1 with 32 bytes of data:
Reply from 192.168.1.1: bytes=32 time=0ms TTL=126
Reply from 192.168.1.1: bytes=32 time=1ms TTL=126
Reply from 192.168.1.1: bytes=32 time=11ms TTL=126
Reply from 192.168.1.1: bytes=32 time=0ms TTL=126
Ping statistics for 192.168.1.1:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 0ms, Maximum = 11ms, Average = 3ms
Traceroute dari Laptop2 ke Laptop1
Laptop2>tracert 192.168.1.1
Tracing route to 192.168.1.1 over a maximum of 30 hops:
1 1 ms 0 ms 0 ms 192.168.2.254
2 0 ms 0 ms 0 ms 12.12.12.1
3 1 ms 11 ms 11 ms 192.168.1.1
Trace complete.
Tampilkan routing table spesifik OSPF di R1 dan R2
R1#show ip route ospf
172.16.0.0/16 is variably subnetted, 4 subnets, 2 masks
O 172.16.3.3 [110/2] via 12.12.12.2, 00:05:11, FastEthernet1/0
O 172.16.4.4 [110/2] via 12.12.12.2, 00:05:11, FastEthernet1/0
O 192.168.2.0 [110/2] via 12.12.12.2, 00:04:20, FastEthernet1/0
R1#
R2#show ip route ospf
172.16.0.0/16 is variably subnetted, 4 subnets, 2 masks
O 172.16.1.1 [110/2] via 12.12.12.1, 00:05:05, FastEthernet1/0
O 172.16.2.2 [110/2] via 12.12.12.1, 00:05:05, FastEthernet1/0
O 192.168.1.0 [110/2] via 12.12.12.1, 00:05:05, FastEthernet1/0
R2#
Debug OSPF di R1
05:53:59: %OSPF-5-ADJCHG: Process 1, Nbr 172.16.4.4 on FastEthernet1/0 from
LOADING to FULL, Loading Done
Setelah selesai setting OSPF di R2 step Halaman 53, di R1 maupun R2 akan muncul output
adjacent router OSPF. Dari output debug OSPF diatas R1 memiliki neighbor 172.16.4.4.
172.16.4.4 adalah router ID dari R2. Berarti R1 dan R2 telah menjalin relationship neighbor
(adjacency) sehingga routing update akan saling dikirimkan.
Setting router-id OSPF di R1
R1(config)#router ospf 1
R1(config-router)#router-id 111.111.111.111
R1(config-router)#Reload or use "clear ip ospf process" command, for this to
take effect
R1(config-router)#
Setting router-id OSPF di R2
R2(config)#router ospf 1
R2(config-router)#router-id 222.222.222.222
R2(config-router)#Reload or use "clear ip ospf process" command, for this to
take effect
R2(config-router)#
Setelah menjalankan command router-id diatas, jalankan command clear ip ospf
process untuk mereset proses OSPF di R1 maupun R2, sehingga router-id OSPF akan berubah.
R1#clear ip ospf process
Reset ALL OSPF processes? [no]: yes
R1#
06:12:37: %OSPF-5-ADJCHG: Process 1, Nbr 172.16.4.4 on FastEthernet1/0 from FULL
to DOWN, Neighbor Down: Adjacency forced to reset
06:12:37: %OSPF-5-ADJCHG: Process 1, Nbr 172.16.4.4 on FastEthernet1/0 from FULL
to DOWN, Neighbor Down: Interface down or detached
R1#
06:12:41: %OSPF-5-ADJCHG: Process 1, Nbr 172.16.4.4 on FastEthernet1/0 from
LOADING to FULL, Loading Done
Tampilkan neighbor table OSPF di R1
R1#show ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
222.222.222.222 1 FULL/DR 00:00:36 12.12.12.2 FastEthernet1/0
R1#
Dari output neighbor table di R1, bisa kita lihat di kolom neighbor ID terdapat 222.222.222.222,
dimana 222.222.222.222 adalah router-id R2. Dengan demikian, setting router-id OSPF di R2 telah
berhasil.
Note: ulangi langkah yang sama diatas untuk mereset process OSPF dan tampilkan
neighbor table OSPF di R2, pastikan neighbor ID R1 111.111.111.111
Setting passive-interface OSPF di R1
R1(config)#router ospf 1
R1(config-router)#passive-interface fa0/0
R1(config-router)#
Tampilkan routing information OSPF di R1
R1#show ip protocols
Routing Protocol is "ospf 1"
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Router ID 111.111.111.111
Number of areas in this router is 1. 1 normal 0 stub 0 nssa
Maximum path: 4
Routing for Networks:
12.12.12.0 0.0.0.255 area 0
172.16.1.0 0.0.0.255 area 0
172.16.2.0 0.0.0.255 area 0
192.168.1.0 0.0.0.255 area 0
Passive Interface(s):
FastEthernet0/0
Routing Information Sources:
Gateway Distance Last Update
111.111.111.111 110 00:11:04
172.16.2.2 110 00:30:11
172.16.4.4 110 00:11:38
222.222.222.222 110 00:11:04
Distance: (default is 110)
Passive-interface fa0/0 telah berhasil ditambahkan di OSPF R1.
Tampilkan interface OSPF di R1
R1#show ip ospf interface
FastEthernet1/0 is up, line protocol is up
Internet address is 12.12.12.1/24, Area 0
Process ID 1, Router ID 111.111.111.111, Network Type BROADCAST, Cost: 1
Transmit Delay is 1 sec, State BDR, Priority 1
Designated Router (ID) 222.222.222.222, Interface address 12.12.12.2
Backup Designated Router (ID) 111.111.111.111, Interface address 12.12.12.1
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
Hello due in 00:00:07
Index 1/1, flood queue length 0
Next 0x0(0)/0x0(0)
Last flood scan length is 1, maximum is 1
Last flood scan time is 0 msec, maximum is 0 msec
Neighbor Count is 1, Adjacent neighbor count is 1
Adjacent with neighbor 222.222.222.222 (Designated Router)
Suppress hello for 0 neighbor(s)
Loopback1 is up, line protocol is up
Internet address is 172.16.1.1/24, Area 0
Process ID 1, Router ID 111.111.111.111, Network Type LOOPBACK, Cost: 1
Loopback interface is treated as a stub Host
Loopback2 is up, line protocol is up
Internet address is 172.16.2.2/24, Area 0
Process ID 1, Router ID 111.111.111.111, Network Type LOOPBACK, Cost: 1
Loopback interface is treated as a stub Host
FastEthernet0/0 is up, line protocol is up
Internet address is 192.168.1.254/24, Area 0
Process ID 1, Router ID 111.111.111.111, Network Type BROADCAST, Cost: 1
Transmit Delay is 1 sec, State WAITING, Priority 1
No designated router on this network
No backup designated router on this network
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
No Hellos (Passive interface)
Index 4/4, flood queue length 0
Next 0x0(0)/0x0(0)
Last flood scan length is 1, maximum is 1
Last flood scan time is 0 msec, maximum is 0 msec
Neighbor Count is 0, Adjacent neighbor count is 0
Suppress hello for 0 neighbor(s)
Passive-interface OSPF memiliki kemiripan dengan EIGRP. Dengan mengaktifkan passiveinterface
di interface OSPF, maka akan menghentikan pengiriman paket hello sehingga akan
mencegah router membentuk relationship neighbor antar router, akibatnya router akan berhenti
melakukan update routing outgoing dan incoming (tidak dapat mengirimkan update routing dan
tidak dapat dikirimi update routing).
OSPF dan EIGRP sama-sama menggunakan paket hello sebelum membentuk relationship antar
router. Perhatikan informasi interface OSPF Fa0/0 dan Fa1/0 R1 diatas. Fa0/0 sudah diaktifkan
command passive-interface sehingga tidak ada lagi paket hello. Beda dengan Fa1/0 yang
ada keterangan Hello due in..
FastEthernet0/0 is up, line protocol is up
No Hellos (Passive interface)
FastEthernet1/0 is up, line protocol is up
Hello due in 00:00:07
Karena Network A dan Network B merupakan jaringan LAN dimana tidak membutuhkan
relationship neighbor antar router OSPF sehingga tidak jadi masalah ketika interface Fa0/0
diaktifkan command passive-interface-nya. Lain halnya dengan interface Fa1/0 ketika
diaktifkan command passive-interface, maka akan menimbulkan masalah yaitu R1 tidak
dapat membentuk relationship dengan R2, sehingga OSPF tidak dapat berjalan normal.
OSPF secara default memiliki hello interval = 10 second, dan dead interval = 40 second.
Interface Loopback di OSPF
Perhatikan sekali lagi output routing table di R1 dan R2. Apakah ada masalah dengan interface
loopback?
R1#show ip route
Codes: C - connected, S - static, I - IGRP, 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, E - EGP
i - IS-IS, 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
Gateway of last resort is not set
12.0.0.0/24 is subnetted, 1 subnets
C 12.12.12.0 is directly connected, FastEthernet1/0
172.16.0.0/16 is variably subnetted, 4 subnets, 2 masks
C 172.16.1.0/24 is directly connected, Loopback1
C 172.16.2.0/24 is directly connected, Loopback2
O 172.16.3.3/32 [110/2] via 12.12.12.2, 00:38:50, FastEthernet1/0
O 172.16.4.4/32 [110/2] via 12.12.12.2, 00:38:50, FastEthernet1/0
C 192.168.1.0/24 is directly connected, FastEthernet0/0
O 192.168.2.0/24 [110/2] via 12.12.12.2, 00:38:50, FastEthernet1/0
R2#show ip route
Codes: C - connected, S - static, I - IGRP, 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, E - EGP
i - IS-IS, 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
Gateway of last resort is not set
12.0.0.0/24 is subnetted, 1 subnets
C 12.12.12.0 is directly connected, FastEthernet1/0
172.16.0.0/16 is variably subnetted, 4 subnets, 2 masks
O 172.16.1.1/32 [110/2] via 12.12.12.1, 00:41:42, FastEthernet1/0
O 172.16.2.2/32 [110/2] via 12.12.12.1, 00:41:42, FastEthernet1/0
C 172.16.3.0/24 is directly connected, Loopback3
C 172.16.4.0/24 is directly connected, Loopback4
O 192.168.1.0/24 [110/2] via 12.12.12.1, 00:41:42, FastEthernet1/0
C 192.168.2.0/24 is directly connected, FastEthernet0/0
R2#
Loopback1 is up, line protocol is up
.
Process ID 1, Router ID 111.111.111.111, Network Type LOOPBACK, Cost: 1
Loopback interface is treated as a stub Host
Loopback2 is up, line protocol is up
.
Process ID 1, Router ID 111.111.111.111, Network Type LOOPBACK, Cost: 1
Loopback interface is treated as a stub Host
Loopback3 is up, line protocol is up
.
Process ID 1, Router ID 222.222.222.222, Network Type LOOPBACK, Cost: 1
Loopback interface is treated as a stub Host
Loopback4 is up, line protocol is up
.
Process ID 1, Router ID 222.222.222.222, Network Type LOOPBACK, Cost: 1
Loopback interface is treated as a stub Host
O 172.16.3.3/32 [110/2] via 12.12.12.2, 00:38:50, FastEthernet1/0
O 172.16.4.4/32 [110/2] via 12.12.12.2, 00:38:50, FastEthernet1/0
O 172.16.1.1/32 [110/2] via 12.12.12.1, 00:41:42, FastEthernet1/0
O 172.16.2.2/32 [110/2] via 12.12.12.1, 00:41:42, FastEthernet1/0
Semua loopback, yaitu Loopback1, Loopback2, Loopback3, Loopback4 menjadi stub host dengan network
type LOOPBACK. Stub host memang tampil di routing table dengan prefix /32, akan tetapi tidak dapat
digunakan untuk forwarding.
Agar semua loopback dapat di advertise oleh OSPF sebagai network dengan prefix aslinya yaitu /24, caranya
dengan mengubah network type loopback menjadi point-to-point.
Ubah Network Type Interface Loopback OSPF di R1 dan R2
R1(config)#interface lo1
R1(config-if)#ip ospf network point-to-point
R1(config-if)#
R1(config-if)#interface lo2
R1(config-if)#ip ospf network point-to-point
R1(config-if)#
R2(config)#interface lo3
R2(config-if)#ip ospf network point-to-point
R2(config-if)#
R2(config-if)#interface lo4
R2(config-if)#ip ospf network point-to-point
R2(config-if)#
Tampilkan routing table OSPF terupdate di R1 dan R2
R1#show ip route
Codes: C - connected, S - static, I - IGRP, 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, E - EGP
i - IS-IS, 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
Gateway of last resort is not set
12.0.0.0/24 is subnetted, 1 subnets
C 12.12.12.0 is directly connected, FastEthernet1/0
172.16.0.0/24 is subnetted, 4 subnets
C 172.16.1.0 is directly connected, Loopback1
C 172.16.2.0 is directly connected, Loopback2
O 172.16.3.0 [110/2] via 12.12.12.2, 00:01:00, FastEthernet1/0
O 172.16.4.0 [110/2] via 12.12.12.2, 00:00:50, FastEthernet1/0
C 192.168.1.0/24 is directly connected, FastEthernet0/0
O 192.168.2.0/24 [110/2] via 12.12.12.2, 01:17:07, FastEthernet1/0
R1#
R2#show ip route
Codes: C - connected, S - static, I - IGRP, 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, E - EGP
i - IS-IS, 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
Gateway of last resort is not set
12.0.0.0/24 is subnetted, 1 subnets
C 12.12.12.0 is directly connected, FastEthernet1/0
172.16.0.0/24 is subnetted, 4 subnets
O 172.16.1.0 [110/2] via 12.12.12.1, 00:04:33, FastEthernet1/0
O 172.16.2.0 [110/2] via 12.12.12.1, 00:04:23, FastEthernet1/0
C 172.16.3.0 is directly connected, Loopback3
C 172.16.4.0 is directly connected, Loopback4
O 192.168.1.0/24 [110/2] via 12.12.12.1, 01:18:04, FastEthernet1/0
C 192.168.2.0/24 is directly connected, FastEthernet0/0
Dari output diatas, semua loopback telah diadvertise sebagai network dengan prefix /24.
Selanjutnya kita akan tes Ping dari Loopback1 di R1 ke Loopback3 di R2.
Tes Ping dari Loopback1 di R1 ke Loopback3 di R2
Untuk mencoba tes Ping dari Loopback, gunakan extended-ping di router.
R1#ping
Protocol [ip]: ip
Target IP address: 172.16.3.3
Repeat count [5]: [ENTER]
Datagram size [100]: [ENTER]
Timeout in seconds [2]: [ENTER]
Extended commands [n]: y
Source address or interface: loopback1
Type of service [0]: [ENTER]
Set DF bit in IP header? [no]: [ENTER]
Validate reply data? [no]: [ENTER]
Data pattern [0xABCD]: [ENTER]
Loose, Strict, Record, Timestamp, Verbose[none]:
Sweep range of sizes [n]: [ENTER]
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.3.3, timeout is 2 seconds:
Packet sent with a source address of 172.16.1.1
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 0/0/0 ms
Note: ulangi langkah yang sama diatas untuk tes Ping dari Loopback4 di R2 ke Loopback2
di R1.
Semoga Bermanfaat :-)
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