Task 1: Configure R1 and R2 router IDs using the interface IP addresses from the link that is shared between them.

On R1:

R1#configure terminal
R1(config)#router ospf 1
R1(config-router)#router-id 192.168.1.1

This command manually configures the router-id of R1 as 192.168.1.1, which is the IP address of the GigabitEthernet0/0 interface of R1.

On R2:

R2#configure terminal
R2(config)#router ospf 1
R2(config-router)#router-id 192.168.1.2

This command manually configures the router-id of R1 as 192.168.1.2, which is the IP address of the GigabitEthernet0/0 interface of R2.

Task 2: Configure R3's router ID using it's loopback0 IP address.

On R3:

R3#configure terminal
R3(config)#router ospf 1
R3(config-router)#router-id 10.0.0.3

This command manually configures the router-id of R3 as 10.0.0.3, which is the IP address of the loopback0 interface of R2.

Task 3: Configure OSPF on the routers to form neighbor relationships with each other in area 0 without using the network command.

Instead of the network command, ip ospf area command can be used under each interface.

On R1:

R1(config-router)#interface range g0/0-1
R1(config-if)#ip ospf 1 area 0

On R2:

R2(config-router)#interface range g0/0-1
R2(config-if)#ip ospf 1 area 0

On R3:

R3(config-router)#interface range g0/0-1
R3(config-if)#ip ospf 1 area 0

The interface range f0/1-3 command allows us to configure the interfaces collectively which can save a lot of time. ip ospf 1 area 0 command allows the interfaces to participate in OSPF by sending and receiving OSPF Hello packets to form neighbor relationships and advertise the directly connected network.

Task 4: Configure OSPF on router R3 to advertise its loopback0 address in OSPF Area 0 without using the network command.

We can configure R3 to advertise it's loopback0 address by enabling OSPF on the loopback0 interface.

On R3:

R3(config-if)#interface loopback0
R3(config-if)#ip ospf 1 area 0

Verification:

Check the neighbour adjacencies by using show ip ospf neighbor command on any of the devices.

R1(config-if)end
R1#show ip ospf neighbor

Neighbor ID     Pri   State           Dead Time   Address         Interface

192.168.1.2       1   FULL/DR         00:00:32    192.168.1.2     GigabitEthernet0/0

10.0.0.3          1   FULL/BDR        00:00:37    192.168.3.2     GigabitEthernet0/1

Check the Routing table to see if there is a route to R3's loopback0 address.

R1#show ip route ospf

     10.0.0.0/32 is subnetted, 1 subnets

O       10.0.0.3 [110/2] via 192.168.3.2, 00:02:12, GigabitEthernet0/1

     192.168.2.0/30 is subnetted, 1 subnets

O       192.168.2.0 [110/2] via 192.168.3.2, 00:02:12, GigabitEthernet0/1

                    [110/2] via 192.168.1.2, 00:02:12, GigabitEthernet0/0

Now exit the configuration mode and save the configuration.

R1#write memory

R2(config)#end
R2#write memory

R3(config)#end
R3#write memory