Configure OSPF on unnumbered interfaces

 

When we've been assigning router interfaces in OSPF areas with the network router configuration command, it was impossible to start OSPF only on some unnumbered interfaces and not on others (or place the unnumbered interfaces in different areas). These restrictions are removed if you use the ip ospf area interface configuration command. For example, to put the loopback interface into another area than the WAN links using its IP address, use the following configuration commands:

router ospf 1
!
interface Loopback0
 ip address 
10.0.0.3 255.255.255.255
 ip ospf 1 area 
0
!
interface Serial1/0
 ip unnumbered Loopback0
 ip ospf 1 area 1
!
interface Serial1/1
 ip 
unnumbered Loopback0
 ip ospf 1 area 
2

Posted to Cisco IOS Hints and Tricks by IvanPepelnjak
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