Do Ping to an shutdown interface

[kevingcfcb88]

Hi... I have a problem with a topology, I'm student and i have one doubt about this subject particularly...

The topology is configured in that way, but, i have to shutdown the interface in the red circle, and make ping from the R1 to that interface althought is shutdown... My teacher saids that can be done with a loopback in R3 but i can't make it work....

Can somebody help me?

[andrew.prince]

Kevin,

The link beween R2 and R3 is a serial connection? Running ppp encapsualtion correct???

[kevingcfcb88]

Is a FastEthernet connection... RIPv2...

[jimmysands73_2]

If the interface is shutdown I do not believe it will still respond to pings.....but I could be wrong or misunderstanding your question.

[kevingcfcb88]

That's correct, can't do ping because is down, but exist a mecanism, to do ping with the loopback, my teacher saids, because he do it, but can't tell men, he show me and yes it's posible... But i don't know how to it????

[jimmysands73_2]

I am guessing keepalives, but in looking this up, that is not the answer....so please post when you find this out

I still do not see how if an interface is shutdown.  Will prove bery interesting...

[andrew.prince]

Is the link was a serial connection, running ppp encapsulation then there is a solution.  You create a loop back interface and configure the ip address.  Then you use the " ip unnumbered loop back" command.

As the ip s on the loopback and the serial interface just borrows it, you can shut the serial interface and ping will still work.

Not sure you can do the same thing with an Ethernet interface.

[glen.grant]

   You cant ping the  interface that you shutdown if its admin down what your teacher is saying is that you should be able to ping a loopback address in R3  which is correct.  A loopback address is always in a up/up condition .   You just need to get routing working correctly around the other path to get to that  router.   Further investigation I think Andrew may have hit on it.  What you might be able to do is create a loopback interface and then use the ip unnumbered command on it using your serial interface address  as the source  , so it  would like . 

http://www.cisco.com/en/US/tech/tk648/tk362/technologies_tech_note09186a0080094e8d.shtml

interface loop 0

ip unnumbered 

[kevingcfcb88]

Than can be done by static route? or rip too? And exist some way to put the same ip in the interface and loopback?

[kevingcfcb88]

That can be done in serial interfaces, but i have FastEthernet interfaces on all the topology...