5.4.10.2 Cable tester
cable_diag ports <PORT_LIST>
<PORT_LIST> – the port on which the diagnostics are performed
The cable tester is used to monitor the integrity of the UTP/FTP cable on Fast
Ethernet ports.
PSW switches support the function of checking the integrity of the cable on the
Fast Ethernet ports. This test determines the type of fault (cutoff or short circuit) for
each pair, and also specify the distance from the switch to the fault location.
The physical principle of testing relies on the fact that the switch sends a test
electrical impulse over the cable, and on the basis of the delay time and the phase of
the received reflected signal determines the distance to the fault and its type.
For
that period of time, the connection and the link on the tested port are intermitted.
If the cable is fault-free and the properly functioning network device is
connected to the other side, it is not possible to measure cable length this way,
because test signal will be terminated by the end device and will not be a reflection.
Possible testing results:
Short
– Short circuit between pairs
Open
– Break or cable is not connected
Good
– there is no fault.
