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You are configuring Open Shortest Path First (OSPF) protocol for IPv6 on Router5. The router has two
interfaces, which have been configured as follows:
S0/0 – 192.168.5.1/24
S0/1 – 10.0.0.6/8
You would like OSPF to route for IPv6 only on the S0/0 network and not route for IPv6 on the S0/1 network.
The process ID you have chosen to use is 25. You do not want to apply an IPv6 address yet.
Which of the following command sets would enable OSPF for IPv6 as required?

A. Router5(config)#ipv6 ospf 25
Router5(config)# network 192.168.5.0

B. Router5(config)#ipv6 ospf 25
Router5(config)#router-id 192.168.5.1

C. Router5(config)#ipv6 unicast-routing
Router5(config)#ipv6 router ospf 25
Router5(config-rtr)#router-id 1.1.1.1
Router5(config)#interface S0/0
Router5(config-if)#ipv6 ospf 25 area 0

D. Router5(config)#ipv6 unicast-routing
Router5(config)#ipv6 ospf 25
Router5(config-rtr)#router-id 1.1.1.1

Explanation:
The correct command sequence would be as follows:
Router5(config)# ipv6 unicast-routing
Router5(config)# ipv6 router ospf 25
Router5(config-rtr)# router-id 1.1.1.1
Router5(config)# interface S0/0
Router5(config-if)# ipv6 ospf 25 area 0
The first line enables IPv6 routing with the ipv6 unicast-routing command. The second line enables OSPF
routing for IPv6 with the ipv6 router ospf command. The third assigns a necessary router ID (which was
chosen at random) with the router-id command. The last two lines enable OSPF for area 0 on the proper
interface.
The following command set is incorrect because it does not enable OSPF routing for IPv6, assign a
necessary router ID, or enable OSPF for area 0 on the proper interface:
Router5(config)# ipv6 ospf 25
Router5(config)# network 192.168.5.0
This command set also displays incorrect use of the network command. The network command would be
used with OSPF v2.
The following command set fails to enable OSPF routing for IPv6, assign a necessary router ID, or enable
OSPF for area 0 on the proper interface:
Router5(config)# ipv6 ospf 25
Router5(config)# router-id 192.168.5.1
It also assigns the router ID under global configuration mode, rather than under router ospf 25 configuration
mode as required.
The following command set fails to enable OSPF for area 0 on the proper interface:
Router5(config)# ipv6 unicast-routing
Router5(config)# ipv6 ospf 25
Router5(config-rtr)# router-id 1.1.1.1
Objective:
Layer 3 Technologies
Sub-Objective:

Configure and verify OSPF for IPv6
References:
Cisco > Implementing OSPF for IPv6 > How to Implement OSPF for IPv6
Cisco > Cisco IOS IPv6 Command Reference > ipv6 unicast-routing
Cisco > Cisco IOS IPv6 Command Reference > ipv6 ospf area

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