Configure OSPF areas as indicated in Figure 3-2.
OSPF load balancing in Area0 will be automatic when configuring R4 to peer with R2/R3 and R1 with R2/R3. OSPF supports equal-cost load balancing by default.
Configure separate OSPF processes on routers behind the PIX/VPN3000. They should not have any link whatsoever.
For R8 not to receive external OSPF routes, we could configure Area20 as stub. Since we are advertising Loopback1 on R8 in RIP and redistributing RIP into OSPF, we need to configure Area20 as NSSA. See Example 3-3.
router ospf 110 router-id 220.127.116.11 area 20 authentication message-digest area 20 nssa redistribute rip metric 10 subnets network 10.1.5.0 0.0.0.255 ...