Example Configuration of Three Networks with OSPF

Author: Jess Cannata


Network setup - three Debian 7 routers, each with three networks

Router rcp100-11

Router rcp100-12

Router rcp100-13

Three PCs (one connected to each router)

OSPF network


Step 1: Default configuration without OSPF, checking the existing routes

Router rcp100-11

rcp100-11#show ip route 
Codes: C - connected, S - static, R - RIP, B - blackhole, O - OSPF
IA - OSPF inter area, E1 - OSPF external type 1, E2 - OSPF external type 2

C    192.168.201.0/24 is directly connected, eth0
C    192.168.232.0/30 is directly connected, eth1
C    192.168.232.4/30 is directly connected, eth2

startup-config

Router rcp100-12

rcp100-12#show ip route 
Codes: C - connected, S - static, R - RIP, B - blackhole, O - OSPF
IA - OSPF inter area, E1 - OSPF external type 1, E2 - OSPF external type 2

C    192.168.202.0/24 is directly connected, eth0
C    192.168.232.0/30 is directly connected, eth1
C    192.168.232.8/30 is directly connected, eth2

startup-config

Router rcp100-13

rcp100-13#show ip route 
Codes: C - connected, S - static, R - RIP, B - blackhole, O - OSPF
IA - OSPF inter area, E1 - OSPF external type 1, E2 - OSPF external type 2

C    192.168.203.0/24 is directly connected, eth0
C    192.168.232.4/30 is directly connected, eth1
C    192.168.232.8/30 is directly connected, eth2

startup-config


Step 2: Ping from one client (v13) to another (v11)

root@v13:~# ping 192.168.201.5
PING 192.168.201.5 (192.168.201.5) 56(84) bytes of data.
From 192.168.203.15 icmp_seq=1 Destination Net Unreachable
From 192.168.203.15 icmp_seq=2 Destination Net Unreachable
--- 192.168.201.5 ping statistics ---
2 packets transmitted, 0 received, +2 errors, 100% packet loss, time 999ms

Step 3: OSPF Configuration

Router rcp100-11

router ospf
  router-id 192.168.232.5
  network 192.168.232.0/30 area 0
  network 192.168.232.4/30 area 0
  network 192.168.201.0/24 area 0

startup-config

Router rcp100-12

router ospf
  router-id 192.168.232.9
  network 192.168.202.0/24 area 0
  network 192.168.232.0/30 area 0
  network 192.168.232.8/30 area 0

startup-config

Router rcp100-13

router ospf
  router-id 192.168.232.10
  network 192.168.203.0/24 area 0
  network 192.168.232.4/30 area 0
  network 192.168.232.8/30 area 0

startup-config


Step 4: Show all routes

Router rcp100-11

rcp100-11#show ip route 
Codes: C - connected, S - static, R - RIP, B - blackhole, O - OSPF
IA - OSPF inter area, E1 - OSPF external type 1, E2 - OSPF external type 2

C    192.168.201.0/24 is directly connected, eth0
O    192.168.202.0/24[110/2] via 192.168.232.2, eth1
O    192.168.203.0/24[110/2] via 192.168.232.6, eth2
C    192.168.232.0/30 is directly connected, eth1
C    192.168.232.4/30 is directly connected, eth2
O    192.168.232.8/30[110/2] via 192.168.232.2, eth1
                             via 192.168.232.6, eth2

Router rcp100-12

rcp100-12#show ip route 
Codes: C - connected, S - static, R - RIP, B - blackhole, O - OSPF
IA - OSPF inter area, E1 - OSPF external type 1, E2 - OSPF external type 2

O    192.168.201.0/24[110/2] via 192.168.232.1, eth1
C    192.168.202.0/24 is directly connected, eth0
O    192.168.203.0/24[110/2] via 192.168.232.10, eth2
C    192.168.232.0/30 is directly connected, eth1
O    192.168.232.4/30[110/2] via 192.168.232.1, eth1
                             via 192.168.232.10, eth2
C    192.168.232.8/30 is directly connected, eth2

Router rcp100-13

rcp100-13#show ip route 
Codes: C - connected, S - static, R - RIP, B - blackhole, O - OSPF
IA - OSPF inter area, E1 - OSPF external type 1, E2 - OSPF external type 2

O    192.168.201.0/24[110/2] via 192.168.232.5, eth1
O    192.168.202.0/24[110/2] via 192.168.232.9, eth2
C    192.168.203.0/24 is directly connected, eth0
O    192.168.232.0/30[110/2] via 192.168.232.5, eth1
                             via 192.168.232.9, eth2
C    192.168.232.4/30 is directly connected, eth1
C    192.168.232.8/30 is directly connected, eth2

Step 5: Ping from one client (v13) to another (v11)

root@v13:~# ping 192.168.201.5
PING 192.168.201.5 (192.168.201.5) 56(84) bytes of data.
64 bytes from 192.168.201.5: icmp_req=1 ttl=62 time=1.52 ms
64 bytes from 192.168.201.5: icmp_req=2 ttl=62 time=1.55 ms
--- 192.168.201.5 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1001ms
rtt min/avg/max/mdev = 1.529/1.541/1.553/0.012 ms

Step 6: Test dynamic routing - packets take the shortest path (three hops)

root@v13:~# traceroute 192.168.201.5
traceroute to 192.168.201.5 (192.168.201.5), 30 hops max, 60 byte packets
 1  192.168.203.15 (192.168.203.15)  0.796 ms  0.721 ms  1.938 ms
 2  192.168.232.5 (192.168.232.5)  1.920 ms  1.899 ms  1.879 ms
 3  192.168.201.5 (192.168.201.5)  1.893 ms  1.873 ms  1.853 ms

Step 7: Test dynamic routing - shutdown a Link

rcp100-11(config)#interface ethernet eth2 
rcp100-11(config-if eth2)#shutdown

Step 8: Test dynamic routing - packets take the only available path (four hops)

root@v13:~# traceroute 192.168.201.5
traceroute to 192.168.201.5 (192.168.201.5), 30 hops max, 60 byte packets
 1  192.168.203.15 (192.168.203.15)  0.600 ms  0.591 ms  0.569 ms
 2  192.168.232.9 (192.168.232.9)  1.943 ms  1.935 ms  1.919 ms
 3  192.168.232.1 (192.168.232.1)  1.897 ms  1.895 ms  1.888 ms
 4  192.168.201.5 (192.168.201.5)  2.485 ms  2.544 ms  2.538 ms