OSPF Mindah Jalur
R1
R1(config)#int fastEthernet 0/0
R1(config-if)#ip add 12.12.12.1 255.255.255.0
R1(config-if)#no sh
R1(config-if)#ex
R1(config)#int gigabitEthernet 2/0
R1(config-if)#ip add 13.13.13.1 255.255.255.0
R1(config-if)#no sh
R1(config)#int lo0
R1(config-if)#ip add 1.1.1.1 255.255.255.255
R1(config-if)#ex
R1(config)#router ospf 1
R1(config-router)#network 0.0.0.0 255.255.255.255 area 0
R1(config-router)#auto-cost reference-bandwidth 1000
% OSPF: Reference bandwidth is changed.
Please ensure reference bandwidth is consistent across all routers
R2
R2(config)#int fa0/0
R2(config-if)#ip add 12.12.12.2 255.255.255.0
R2(config-if)#no sh
R2(config-if)#exit
R2(config)#int gigabitEthernet 3/0
R2(config-if)#ip add 23.23.23.2 255.255.255.0
R2(config-if)#no sh
R2(config-if)#exit
R2(config)#int lo0
R2(config-if)#ip add 2.2.2.2 255.255.255.255
R2(config-if)#ex
R2(config)#router ospf 2
R2(config-router)#network 0.0.0.0 255.255.255.255 area 0
R2(config-router)#auto-cost reference-bandwidth 1000
% OSPF: Reference bandwidth is changed.
Please ensure reference bandwidth is consistent across all routers
R3
R3(config)#int g2/0
R3(config-if)#ip add 23.23.23.3 255.255.255.0
R3(config-if)#no sh
R3(config-if)#ex
R3(config)#int G3/0
R3(config-if)#ip add 13.13.13.3 255.255.255.0
R3(config-if)#no sh
R3(config-if)#ex
R3(config)#int lo0
R3(config-if)#ip add 3.3.3.3 255.255.255.255
R3(config-if)#exit
R3(config)#router ospf 3
R3(config-router)#network 0.0.0.0 255.255.255.255 area 0
R3(config-router)#auto-cost reference-bandwidth 1000
R1
R1(config)#do traceroute 2.2.2.2
Type escape sequence to abort.
Tracing the route to 2.2.2.2
VRF info: (vrf in name/id, vrf out name/id)
1 13.13.13.3 8 msec 88 msec 12 msec
2 23.23.23.2 40 msec 32 msec 32 msec
R1
R1#show ip route 2.2.2.2
Routing entry for 2.2.2.2/32
Known via "ospf 1", distance 110, metric 3, type intra area
Last update from 13.13.13.3 on GigabitEthernet2/0, 00:41:25 ago
Routing Descriptor Blocks:
* 13.13.13.3, from 2.2.2.2, 00:41:25 ago, via GigabitEthernet2/0
Route metric is 3, traffic share count is 1
Nah menurut informasi di atas nih temen-temen, jalur yang mengarah ke R2
itu melalui R3 terlebih dahulu, kenapaaaa ?? karena OSPF menggunakan
bandwidth,. Dimana link gigabitethernet tentu nya lebih di pilih di banding
dengan melalui interface fastethernet, selanjutnya perhatikan pada bagian
metric nya yang bernilai 3, nilai 3 di dapatkan dari penjumlahan berikut.
(metric Link gigabitethernet R1-R3) + (metric link gigabitethernet R3-R2) +
(metric loopback R3,.
1 + 1 + 1 = 3
Nilai 1 berasal dari pembagian 1000.000.000 : 1000.000.000 (reference
bandwidth nya sudah di rubah menjadi 1000Mbps), berikutnya kita shutdown
terleih dahulu interface Gigabitethernet nya
R1
R1(config)#int g2/0
R1(config-if)#shutdown
R1(config-if)#exit
R1
R1(config)#do traceroute 2.2.2.2
Type escape sequence to abort.
Tracing the route to 2.2.2.2
VRF info: (vrf in name/id, vrf out name/id)
1 12.12.12.2 56 msec 64 msec 20 msec
R1
R1#show ip route 2.2.2.2
Routing entry for 2.2.2.2/32
Known via "ospf 1", distance 110, metric 11, type intra area
Last update from 12.12.12.2 on FastEthernet0/0, 00:02:57 ago
Routing Descriptor Blocks:
* 12.12.12.2, from 2.2.2.2, 00:02:57 ago, via FastEthernet0/0
Route metric is 11, traffic share count is 1
Perhatikan pada metric nya yakni 11 merupakan penambahan link
fastethernet R1-R2+link Lopback R3 (10+1). Nilai 10 didapat dari hasil
pembagian 100.000.000:100.000.000 = 10
coba shutdown lagi gigabyte ethernetnya.
R1
R1(config)#int g2/0
R1(config-if)#no sh
R1(config-if)#ex
Dan pastikan jalur yang di lewati R1 untuk menuju R2 melewati R3 kembali,
R1
R1(config)#do sh ip route 2.2.2.2
Routing entry for 2.2.2.2/32
Known via "ospf 1", distance 110, metric 3, type intra area
Last update from 13.13.13.3 on GigabitEthernet2/0, 00:00:08 ago
Routing Descriptor Blocks:
* 13.13.13.3, from 2.2.2.2, 00:00:08 ago, via GigabitEthernet2/0
Route metric is 3, traffic share count is 1
Selanjutnya kita akan rubah bandwith Gigabitethernet menjadi 1000 agar ospf
akan lewat langsung ke R2
R1
R1(config-if)#int g2/0
R1(config-if)#bandwidth 1000
Maka jalur akan berpindah langsung lewat R2 tidak melewati R3,.
R1
R1(config)#do sh ip route 2.2.2.2
Routing entry for 2.2.2.2/32
Known via "ospf 1", distance 110, metric 11, type intra area
Last update from 12.12.12.2 on FastEthernet0/0, 00:01:25 ago
Routing Descriptor Blocks:
* 12.12.12.2, from 2.2.2.2, 00:01:25 ago, via FastEthernet0/0
Route metric is 11, traffic share count is 1
selesai
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