Router1#sh ip os int b
Interface PID Area IP Address/Mask Cost State Nbrs F/C
Vl50 1 0 161.1.79.7/24 300 DR 1/1
Fa0/15 1 0 161.1.78.7/24 100 BDR 1/1
Lo0 1 0 150.1.7.7/24 1 LOOP 0/0
Router2#sh ip os int b
Interface PID Area IP Address/Mask Cost State Nbrs F/C
Fa0/16 1 0 161.1.89.8/24 150 DR 1/1
Fa0/15 1 0 161.1.78.8/24 100 DR 1/1
Lo0 1 0 150.1.8.8/24 1 LOOP 0/0
Router3#sh ip os int b
Interface PID Area IP Address/Mask Cost State Nbrs F/C
Fa0/16 1 0 161.1.89.9/24 150 BDR 1/1
Vl50 1 0 161.1.79.9/24 300 BDR 1/1
Lo0 1 0 150.1.9.9/24 1 LOOP 0/0
Router3#sh ip ro 150.1.7.7
Routing entry for 150.1.7.7/32
Known via "ospf 1", distance 110, metric 251, type intra area
Last update from 161.1.89.8 on FastEthernet0/16, 00:04:39 ago
Routing Descriptor Blocks:
* 161.1.89.8, from 150.1.7.7, 00:04:39 ago, via FastEthernet0/16
Route metric is 251, traffic share count is 1
Router3#traceroute 150.1.7.7
Type escape sequence to abort.
Tracing the route to 150.1.7.7
1 161.1.89.8 0 msec 4 msec 0 msec
2 161.1.78.7 4 msec * 0 msec
# SCENARIO I, Change cost with 'ip ospf cost 50'
Router3(config)#do sh ip os int b
Interface PID Area IP Address/Mask Cost State Nbrs F/C
Fa0/16 1 0 161.1.89.9/24 150 BDR 1/1
Vl50 1 0 161.1.79.9/24 50 BDR 1/1
Lo0 1 0 150.1.9.9/24 1 LOOP 0/0
Router3(config)#do sh ip ro 150.1.7.7
Routing entry for 150.1.7.7/32
Known via "ospf 1", distance 110, metric 51, type intra area
Last update from 161.1.79.7 on Vlan50, 00:00:36 ago
Routing Descriptor Blocks:
* 161.1.79.7, from 150.1.7.7, 00:00:36 ago, via Vlan50
Route metric is 51, traffic share count is 1
Router3(config)#do traceroute 150.1.7.7
Type escape sequence to abort.
Tracing the route to 150.1.7.7
1 161.1.79.7 4 msec * 0 msec
>> Verify with ping, during I change cost 50
Router3#ping 150.1.7.7 repeat 10000
Success rate is 100 percent (10000/10000), round-trip min/avg/max = 1/1/28 ms
# SCENARIO II, Force shutdown interface FastEternet0/15 in Router1 (Router1-Router2)
traffic from Router3 to Router 1 should be route to interface vlan 50 (Router1-Router3)
Router3(config-if)#do sh ip ro 150.1.7.7
Routing entry for 150.1.7.7/32
Known via "ospf 1", distance 110, metric 301, type intra area
Last update from 161.1.79.7 on Vlan50, 00:00:29 ago
Routing Descriptor Blocks:
* 161.1.79.7, from 150.1.7.7, 00:00:29 ago, via Vlan50
Route metric is 301, traffic share count is 1
Router3(config-if)#do traceroute 150.1.7.7
Type escape sequence to abort.
Tracing the route to 150.1.7.7
1 161.1.79.7 0 msec * 0 msec
>> Verify with ping, during I force shutdown
Router3#ping 150.1.7.7 repeat 10000
Success rate is 99 percent (9995/10000), round-trip min/avg/max = 1/1/216 ms
