Task 1. Configure R3 and R20 so they do not participate in a DR/BDR election process in Area
20.
Area 20 only has two routers so if we use "ip ospf priority 0" command on them (so that they do not participate in DR/BDR election process) then the OSPF process may fail as there is no DR/BDR to process OSPF packets. A better solution is to set OSPF network type to point-to- point.
On R3:
R3(config)#interface e0/1
R3(config-if)#ip ospf network point-to-point
On R20:
R20(config)#interface e0/0
R20(config-if)#ip ospf network point-to-point
Make sure the election is reset on both routers:
R3#,R20#clear ip ospf process
Reset all OSPF processes? [no]: y
Verification
On both R3 and R20 use the "show ip ospf neighbor" command, we will see both neighbors show the "DROTHER" state. For example on R3:
R3#show ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
...
10.2.203.20 0 FULL/- 00:00:10 10.2.203.20 Ethernet0/1
Note: We should check the "Address" field (as the "Neighbor ID" field does not show what is the router clearly) to identify the neighbor. In the above output, from the "Address" field of
10.2.203.20, we can identify this is R20.
Task 2. Configure R10 so it is always the DR for Area 10. Do not change the router ID.
We can configure R10 to be the DR with highest OSPF priority value:
R10(config)#interface e0/0
R10(config-if)#ip ospf priority 255
Make sure the election is reset on R2 & R10:
R2#,R10#clear ip ospf process
Reset all OSPF processes? [no]: y
Verification
On R2 use the "show ip ospf neighbor" command, we will see R10 (with "Address" field of
10.1.102.10) shows the "DR" state.
Save the configuration
We changed the configuration on R3, R10 and R20 so we need to save the configuration on all of them:
R3#,R10#, R20# copy running-config startup-config