I'll try to be brief. I've researched this topic as much as I could on these forums and I've determined that I need to do some loop back tests with this CSU.
We are experiencing various network slowdowns and glitches at one of our remote sites. Truthfully I don't think this particular setup as work right since we cutover to it months ago. We did 11 other sites with the same configuration and no problems. We have a full T1 on a 2811 with a WIC-1DSU-T1-V2. I can't see any problems using show commands, the router's SDM, or CiscoWorks.
Our service provider tested for 4 hrs and said everything up to the Smart Jack looks good, but they do acknowledge high loss of frame coming from this router. The Smart Jack is no more than 100ft. from the router connected with a new dedicated CAT5e UTP cable.
So back to the loopback testing. I gather I need to do (loopback DTE) and (Loopback Line)? As I understand it Loopback DTE with test the router and CSU internally and Loopback line will test to the Smart Jack. Do I clear counters then run the Loopback command for a few minutes, and then do a Show Interface and Show Service-Module?
The site is about a 2hr drive away so if needed I can always head up there but our users need to stay connected during normal business hrs.