Interface ping

Unanswered Question
Feb 28th, 2008

Hi there;

I have a 2811 router interfacing to a 3750. I have multiple serial and fa interfaces on the router. Is it possible, without anything connected to the routing interfaces that I might be able to ping the ip addresses associated with these interfaces? Can a loopback be set maybe? Is there any way to do it?


I have this problem too.
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Richard Burts Thu, 02/28/2008 - 19:28


First let me see if I understand your question correctly: you have a 2811 router connected to a 3750, that interface has an IP address and is active. Your 2811 has other interfaces which also have IP addresses assigned. But these other interfaces are not connected to anything and so the line protocol of these interfaces is down. And since the line protocol is down you can not ping these interface addresses. And you want to do something that will make the other interfaces able to respond to ping. Is this the correct understanding? If not please clarify.

If that is the correct understanding then I have a suggestion: on these other interfaces configure "no keepalive". With no keepalive the line protocol should come up and they should be able to be pinged. I have done this with Ethernet/FastEthernet interfaces and I know that it works. I am less confident about the serial interfaces. It may be that the serial interfaces will be interface down as well as line protocol down. In that case the no keepalive may not be sufficient to be able to ping them.



austindaz Thu, 02/28/2008 - 20:15

Hi there;

Yes you are correct on all accounts! Thankyou. Now if I could just get that serial interface up and up then that would be a pretty good result. Maybe I can only do it with an end device plugged in?



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