Open Shortest Path First (OSPF) detected a router that has the same router ID in the area.
The OSPF router ID should be unique. Make sure that all the routers in the area have a unique router ID.
When OSPF initializes, it selects the highest IP address on a router as the router ID for the OSPF process. The router ID uniquely identifies a router within an OSPF domain. If the interface associated with this IP address is ever brought down, or if the address is removed, the OSPF process must recalculate a new router ID and resend all its routing information out its interfaces. If there is not an interface with a valid IP address in an up/up state when it starts, OSPF reports can't allocate router-id error messages to the log.
To display general information about OSPF routing processes, issue the show ip ospf command.
This is sample output with a valid IP address in an up/up state:
Ethernet 0 is up, line protocol is up
Internet Address 192.168.254.202, Mask 255.255.255.0, Area 0.0.0.0
AS 201, Router ID 192.168.99.1, Network Type BROADCAST, Cost: 10
Note: If a loopback interface is configured with an IP address, the Cisco IOS software uses this IP address as its router ID, even if other interfaces have larger IP addresses. Greater stability in the routing table is achieved, because loopback interfaces never go down.