Configure OSPF as shown in Figure 4-3 with MD5 authentication for all areas.
If you do a show ip ospf interface on R6, R7, and R8, you will see the network type is NON-BROADCAST and NBMA does not form adjacency without changing this network type. As you are not to use the ip ospf network command, configure R6 in Area 0 using the neighbor command—that is, unicast OSPF. See Example 4-6.
Summarize RIP external routes on R8 for network(s) 133.72.52.x in OSPF using the summary-address command. See Example 4-7.
Area 2 is not connected to OSPF backbone. Create a virtual link in Area 1 to interconnect Area 2 with MD5 authentication. See Example 4-8.
Redistribute OSPF into RIP on R3 and R4.
Redistribute RIP into ...