Network engineer issues the command #sh int serial; interface status line displays : serial X is up, line protocol down (DCE), how to troubleshoot?

possible problem: missing clock rate interface confg command, failed local or remote CSU/DSU, failed or incorrect cable, router HW failure

troubleshoot: add clock rate int config command on serial interface

step 2: verify correct cable used

step 3: if line protocol still down, possible HW  failure or cabling problem

step 4:rreplacefaulty part as necessary with known good equipment