Loopback and null interface

[sridhar_kamath]

is it neccsary for configure loopback and null interface on the router? and why it is required to do so.

[smahbub]

It isn’t a requirement to configure a loopback interface but it is helpful to diagnose malfunctions between the interface and device.

[pmoulay]

In my humble opionion, it become a must when dealing with OSPF and IBGP. With OSPF because the RID use the highest loopback interface. The same goes for BGP. It is easy to find your neighbors. Help troubleshooting. If you have an additional subnet to spare, it is a good practice. My 2 cents.