serial inteface shows down/down

[gavin han]

>>serial interface up/down

we have private line. serial inteface shows down/down. private line terminates to csu/dsu and than goes to our router. what could be the issue?

serial interface down/down

I checked status yesterday evening and it was showing down/down. what could be the issue? would there be connectivity issue between router and csu/dsu?

[Jeff Van Houten]

Yes

Sent from Cisco Technical Support iPad App

[Collin Clark · Accepted solution]

The link layer is down. Here's a couple of things to check. First replace the cable between the CSU/DSU and the router. Check that the CSU/DSU is functional, try replacing it if you have a spare. Check the smartjack from the carrier and check that there are no red or amber lights. Let us know how that goes.

[gavin han]

We found out that there was telco issue that's why we were seeing down/down status. Telco had mapped the circuit incorrectly.

Now, I'm seeing up/down status. What could be the issue? Telco said their far end cus/dsu is most likely bad so they are going to replace it. Would there be any other reason apart from bad csu/dsu?

Sent from Cisco Technical Support iPad App

[paolo bevilacqua · Accepted solution]

Still telco problem.

[paolo bevilacqua]

circuit failure, complain to telco.

[Mark Combs]

Get a new WIC with a internal CSU/DSU and throw that old ISP junk out the window......  

On a more serious note just as everyone has stated.  You have  Layer 1 issue.  Could be a number of things like router hardware, line hardware, CSU/DSU hardware.  Work your way from the ground up.  Did you check syslogs?  what about error messages or crash info on the flash?  Has the router been recently rebooted due to power outages or similar.  You gotta help us out here not just blasting a message saying "help my router is down"

And the million dollar question........Is the router plugged in?????