Use the CTP "Monitor" function from the Main menu to view these signals.
Input Signal
Value Displayed
RS (Reset)
Normal operating state is "H."
Resets the DSU option hardware.
LL (Local Loopback)
When "L", the DSU hardware is locally looping data
back to the Vanguard hardware.
CL (CSU Loopback)
When "L", the DSU hardware is looping the remote
connection's receive to transmit.
IDL (Idle)
An "H" informs the DSU hardware to send idle bipolar
violations to the remote system.
CLK (Clock Mode)
When "H", denotes network clock use.
When "L", the DSU option provides the clock.
Differences in CTP Statistics
CTP statistics output also differs in the following ways:
•
Detailed Port Statistics show DSU input/output signaling, as well as
noting the installed DSU.
•
Detailed Node Statistics show DSU installation.
CTP Loopback Modes
Two additional CTP loopback modes now exist.
Mode
Function
DSU Internal
Loopback
Does not affect the external interface.
Loops the local transmit data back to the receive data.
Failure indicates no connection.
DSU Internal and
External Loopback
Performs the internal loopback by looping the external
transmit to the external receive to allow manual testing
of the remote interface.
DSU Troubleshooting
Use the following information to help troubleshoot installation problems.
Potential Installation Problems
Installation problems may include the following:
•
Improper telephone company interface connection
•
Incorrect DSU port Clock Source option
•
No signal from telephone company interface