The CE3 and CE4 router configurations are exactly the same. Both are configured in OSPF Area 0 with route redistribution enabled.
The following summarizes the configuration.
device(config)# router ospf device(config-router-ospf-default-vrf)# area 0 device(config-router-ospf-default-vrf)# redistribute connected device(config-router-ospf-default-vrf)# exit device(config)# interface loopback 1 device(config-Loopback-1)# ip address 10.1.1.1/32 device(config-Loopback-1)# exit device(config)# interface loopback 2 device(config-Loopback-2)# ip address 10.1.1.2/32 device(config-Loopback-2)# exit device(config)# interface ethernet 0/1 device(conf-if-eth-0/1)# ip ospf area 0 device(conf-if-eth-0/1)# ip address 10.2.2.1/24 device(config)# interface ethernet 0/2 device(conf-if-eth-0/2)# ip ospf area 0 device(conf-if-eth-0/2)# ip address 10.2.3.1/24