Loopback address for OSPF RouterID

ziggy

: Hi all,

I have found two ways to configure an ip address on the loopback interface which would be required for OSPF and Router ID.

router(config-if)#ip address 192.168.5.2 255.255.255.255

or

router(config-if)#ip address 192.168.5.2 255.255.255.0

I was quite sure that a netmask of 255.255.255.255 was supposed to be used, but am finding conflicts in the resources that I have looked up.

any comments would be appreciated
THANKS

kplab

Both commands can be used to configure the IP address of a loopback interface. The only difference is the subnet mask used (just like issuing the "ip address" command for a physical interface). However, the subnet mask 255.255.255.255 for a loopback interface has the advantage of conserving IP addresses in the network.