Topologia OSPF

La asignación de IPs para RT4 seria:
 

RT4(config)#int fa 0/1
RT4(config-if)# ip add 10.0.0.4 255.255.255.0
RT4(config-if)# no shut
RT4(config-if)#int fa0/0
RT4(config-if)# ip add 192.168.10.4 255.255.255.0
RT4(config-if)# no shut
RT4(config-if)#int fa0/1
RT4(config-if)# no shut
RT4(config-if)#int fa0/1.10
RT4(config-subif)# encapsulation dot1q 10
RT4(config-subif)# ip add 192.168.12.1 255.255.255.0
RT4(config-subif)#int fa0/1.20
RT4(config-subif)# encapsulation dot1q 20
RT4(config-subif)# ip add 192.168.11.1 255.255.255.0

La verificación de esta configuración:

RT4#show ip int brief
Interface IP-Address OK? Method Status Protocol
FastEthernet0/0 192.168.10.4 YES manual up down
FastEthernet0/1 10.0.0.4 YES manual up down
FastEthernet0/1.10 192.168.12.1 YES manual up down
FastEthernet0/1.20 192.168.11.1 YES manual up down
FastEthernet1/0 unassigned YES unset administratively down down

RT4(config-router)# network 192.168.11.0 0.0.0.255 area 100
RT4(config-router)# network 10.0.0.0 0.0.0.255 area 0

RT5(config)#router ospf 1
RT5(config-router)# log-adjacency-changes
RT5(config-router)# network 192.168.10.0 0.0.0.255 area 100
RT5(config-router)# network 192.168.9.0 0.0.0.255 area 100
RT5(config-router)# network 192.168.13.0 0.0.0.255 area 100

MLS1(config)#ip routing
MLS1(config)#router ospf 1
MLS1(config-router)# network 192.168.6.0 0.0.0.255 area 51
MLS1(config-router)# network 192.168.7.0 0.0.0.255 area 51
MLS1(config-router)# network 192.168.5.0 0.0.0.255 area 51

¿De acuerdo a esta información cuales router son Backbone, Internos, ABR o ASBR?