This is part of the CCNP Routing exam. I created 4 OSPF areas that I have placed various subnets into that I will be showing how manual route summarization using the area x range statements work. You cannot use it on area 0. Area 0 must remain intact with the actual routes for OSPF to function. However, areas 1,2, and 3 will get manual route summarization done.
The most interesting one is iosv-3 in area 3. It has two contiguous subnets 192.168.16.0 to 192.168.17.255. These two /24s will become a /23
iosv-3#sh ip int brInterface IP-Address OK? Method Status ProtocolGigabitEthernet0/0 10.255.4.175 YES NVRAM up upGigabitEthernet0/1 unassigned YES unset up upGigabitEthernet0/1.16 192.168.16.2 YES NVRAM up upGigabitEthernet0/1.17 192.168.17.2 YES NVRAM up upGigabitEthernet0/1.161 192.168.16.34 YES NVRAM up upGigabitEthernet0/1.162 192.168.16.66 YES NVRAM up upGigabitEthernet0/1.163 192.168.16.98 YES NVRAM up upGigabitEthernet0/1.164 192.168.16.130 YES NVRAM up upGigabitEthernet0/1.165 192.168.16.162 YES NVRAM up upGigabitEthernet0/1.166 192.168.16.194 YES NVRAM up upGigabitEthernet0/1.167 192.168.16.226 YES NVRAM up upGigabitEthernet0/1.171 192.168.17.34 YES NVRAM up upGigabitEthernet0/1.172 192.168.17.66 YES NVRAM up upGigabitEthernet0/1.173 192.168.17.98 YES NVRAM up upGigabitEthernet0/1.174 192.168.17.130 YES NVRAM up upGigabitEthernet0/1.175 192.168.17.162 YES NVRAM up upGigabitEthernet0/1.176 192.168.17.194 YES NVRAM up upGigabitEthernet0/1.177 192.168.17.226 YES NVRAM up upLoopback0 unassigned YES unset up upiosv-3#
Starting out with no OSPF manual summarization in iosv-1 router ospf 1