What is a loopback?

[12122053]

Hello im new to this so bare with me, thanks. Trying to setup 2 routers with back to back. Someone told me you have to setup the loopback , what is loopback and how do you setup it up? Currently i have 2 routers with serial ports have a blue 60pin cable label on one side DTE and the other says DCE any help, thanks so much.

 

[wybnormal]

To use back to back, you do not need a loopback interface to be configured. The loopback is a logical port that you configure regardless of hardware. It's very useful for a varity of things, OSPF router IDs, DLSW peers, always accessable telnet port and so on.

FOr details on the actual back to back, check out the serial port FAQ here in the forum.

Mike S
"Diplomacy; the art of saying 'nice doggie' till you can find a rock" Wynn Catlin

 

[12122053]

Thank you, wybnormal

 

[12122053]

Hey wybnormal im trying to find the serial FAQ need some help thanks

 

[wybnormal]

Go back to the Cisco Forum main screen where all the tips of listed for this forum ( cisco), then in the upper menu bar is a tab called FAQ. Click on that and it will take you to the Cisco Forum FAQs. It's near the bottom of the list.

Mike S
"Diplomacy; the art of saying 'nice doggie' till you can find a rock" Wynn Catlin

 

[UNIX72]

Thank you once again

 

[vivekd007]

what is loopback interface in cisco routers...what is it's use...and how to do the configuration....can i get some sample configurations

 

[wybnormal]

A loopback interface is a logical interface that the router treats a "real" interface. It's used by many things in the IOS like OSPF as the router ID, DLSW as peer and remote peer address, it contributes to a more stable network with the routing protocols since it doenst "flap" like a frame or other WAN link might, it's good for troubleshooting, tracking your routers via a tool like HP Openview and so on.

interface loopback 0 <ip address> <mask>

Mike S

&quot;Diplomacy; the art of saying 'nice doggie' till you can find a rock&quot; Wynn Catlin