Setting up a loopback address

Oh man! Ad-blocking software has been detected! :'(

This website is run by the community, for the community... and it needs advertisements in order to keep running. Blocking our ads means your killing our stats!
Please disable your ad-block, or become a premium member to hide all advertisements and this notice.

Little help requireed

So i'm messing around with my routers and switches - i've got my laptop connected to my switch which is connected to a cisco 1721 router running dhcp (via fast ethernet port).

The dhcp is working great i'v got an ip and i can ping the gateway. I wanted to set up one of the serial ports as a loopback just so i could pretend its my isp or whatever - so i've configured the interface with an ip and set it to loopback but i cant seem to bring the interface up - no shut doesnt bring it up - i know i've probably made a fatal error, just been googling it to try and find out what that might be - help

 

Oh man! Ad-blocking software has been detected! :'(

This website is run by the community, for the community... and it needs advertisements in order to keep running. Blocking our ads means your killing our stats!
Please disable your ad-block, or become a premium member to hide all advertisements and this notice.

someones just told me somthing needs to be plugged into the serial port to bring it up - i thought maybe as i had it as a loopback, nothing would need to be plugged in ?

 

It is true about the serial connection but you can just have a loopback interface set and it works as you want it.
Just go to
conf t#interface loopback 0
ip address [whatever you whant here]
no shut
end
copy run start
and you shoul be able to ping the IP of the loopback interface

Hope it helps.

 

I'm new to this, but i remember something i read about disabling the keep alive timer on the interface so it will always be up up.... just a thought

 

are you thinking of no-keepalives ?

i agree with albert though on his way to create a loopback is the way I would have done it.

also something would have to be placed in the serial to bring the line protocol up ie HDLC etc if i remember correctly.