Serial Interface keeps flapping on Cisco 2621

[garcia]

Here's the info:

Cisco 2621 ver 12.2 of IOS

T1 DSU/CSU WIC

Clear Channel T1 from Broadwing (Cisco 7513)

Coming off of T3 from Adtran 800 Plus - as a T1

Cross-over t1 cable, pins 1245

B8ZS, ESF, clock source line, channel group ds0 1-24 speed 64, encap HDLC. Configuration done on serial0/0 and service-module t1...

I've got CD on the intfc. The line goes up/up when I plug it in, and then after about 20 secs it goes up/down.

Any ideas?

[Josef Oduwo]

Sounds like a L1 problem. Check the quality of your interface.

Cheers,

Josef.

[garcia]

Quality of my interface? On the mux or on the router? I've tried two different interfaces on the router and two different interfaces on the mux and still the same result. What puzzles me is how it was able to go up/up for 20 secs. If it were cabling or hardware, you'd think that it wouldn't be able to come up at all...

[peterledwidge]

You should try adjust the framing/coding on the line.

If it's a point to point link ensure the other end is configured.

The interface will try and establish a link but drop after 20 secs. This is normal behaviour.

[garcia]

Looks like I needed to actually add the new DS1 to my Adtran Mux's "Dial Plan". After adding the T1 to the map, I saw all NNNNNNNNNNNNNNs under the T1 status screen. The circuit came up immediately after making the change.

So, in conclusion, if you're peeling a DS1 off of a T3 via a MUX, make sure you "enable" the new T1 first before, testing the router's interface...