Loopback of a CISCO Router ?

Question

I am going to do a lab activity in packet tracer.

There is a Loopback in a Core Router which is in the network topology that I am going to configure.I have no idea about what is loopback of a router. What is Loopback of a router ? Why did we set it ? how can we set it in packet tracer ?(commands related to it). What is the use of it ? Please explain any one.

Answer 1

If we were talking about a computer, Aaron would be right, but Aaron is wrong.



A loopback on a router has to be configured as a virtual interface. These have a *lot* of different uses, but to give just one example it can be used as a Router ID in an OSPF process if you don't want OSPF to pick the highest IP address of any physical interface on the router. In general, the loopback address is also the best one to ping to see if the router is up, since otherwise you'd be pinging the IP of a physical interface, and the router might be online via another interface if the one you're polling goes down.



Here's how you configure a loopback interface in Packet Tracer (or on a real router for that matter). In this example I just picked an IP address out of the sky (do NOT pick anything in the 127.x.x.x range since it is reserved for host loopbacks, and the router won't even let you do it):



enable

conf t

interface loopback 0

ip address 10.1.1.1 255.255.255.255

no shutdown

exit

exit

wr



You don't have to, but here I picked a subnet mask of 255.255.255.255, or a "host mask" since the loopback can be thought of as its own single-host network. Also you can make more than one loopback interface if you want.

Answer 2

This Site Might Help You.



RE:

Loopback of a CISCO Router ?

I am going to do a lab activity in packet tracer.



There is a Loopback in a Core Router which is in the network topology that I am going to configure.I have no idea about what is loopback of a router. What is Loopback of a router ? Why did we set it ? how can we set it in packet tracer ?(commands...

Answer 3

Configure Router In Packet Tracer

Answer 4

to do a loopback

ping 127.x.x.x, or just ping 127.0.0.1



It causes the devices to send a packet to itself, it is used to test the network interface for any problems.