interface status

[kpari05]

If you have a T1 to internet lets say going thru a Cisco 1700 router and the link is down. The status on the serial interface is :
serial0 is up, line protocol is down

What exactly does this imply ? When the line protocol is down.....does it point to a Local issue at the customer site [like loose/defective cabling etc] or what does this imply ?

If someone replies to this question, can you also explain what other states on this interface could mean ?
thanks so much
kpari05

 

[hidden75]

I would suggest looking at the interfaces on both ends take a look at the log and also the interface status's. See if you were getting crc, drops, runts, giants, etc...



Next which end is the DTE? DCE?



Check the clock on the DCE side, and check the clock on the DTE side. It could be a cabling issue. It could be a few things.. But start there.


Maybe you can post the show int configurations for both sides.


Maybe you can post the controller information also

 

[jneiberger]

The two states mentioned represent the physical and data link layers, respectively. In this case, the serial interface (physical layer) is up, but the line protocol (datalink layer) is down.

There could be a number of reasons for this. As an example, if a frame relay interface is not receiving LMI from the provider's frame relay switch then the datalink layer will not come up. It might also be that both ends are not configured for the same line protocol, e.g. one side is HDLC while the other is PPP, or one side is Cisco HDLC and the other is a different flavor of HDLC.

Can you post the output of "show interface"? Edit out any information you don't want posted publicly.

 

[kpari05]

Thank you guys. I will post the interface stats in not too long. Appreciate you guys taking the time.
regards,
kpari05