What is the use of Loop Back Interfaces on a Cisco Router??

Question

We can configure number of loop back interfaces on a router, but please tell me the exact use of those interfaces??????

Answer 1

A loopback interface is ALWAYS active and CANNOT fail, that is the reason they are used, they are always in the up/up state and this makes routing protocols such as OSPF and BGP much more stable, as opposed to using a real interface.

In addition, some routing protocols like OSPF will use the highest IP address configured on the router as the router ID, but you can override this behavior by configuring a loopback address.

Finally, you can use the loopback address as the "source interface" for traffic that is generated by the router, such as syslog packets, SNMP traps, and security related packets.

A typical config file's loopback related commands might look like this:
interface Loopback0
ip address 172.16.1.1 255.255.255.255
router ospf 100
router-id 172.16.1.1
ip tftp source-interface Loopback0
ip tacacs source-interface Loopback0
logging source-interface Loopback0
snmp-server trap-source Loopback0

Answer 2

What Is A Loopback Interface

Answer 3

Some virtual networking applications use loopback connections to make a computer think that its connected to a network when it is really just connected to itself.

There are probably other uses as well.

Answer 4

what is the pratical use loopback interface ?
plz elaborate