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7-4
Software Configuration Guide—Release 15.0(2)SG
OL-23818-01
Chapter 7 Checking Port Status and Connectivity
Checking Cable Status Using Time Domain Reflectometer
Note Four pairs of standard category 5 cable exist. Each pair can assume one of the following states: open (not
connected), broken, shorted, or terminated. The TDR test detects all four states and displays the first
three as “Fault” conditions, and displays the fourth as “Terminated.” Although the CLI output is shown,
the cable length is displayed only if the state is “Faulty.”
TDR feature is supported on the following modules:
WS-X4524-GB-RJ45V
WS-X4548-GB-RJ45
WS-X4548-GB-RJ45V
WS-X4548-GB-RJ45V+
WS-X4548-RJ45V+
WS-X4908-10GB-R (only functions on WS-C4900M chassis)
WS-C4948-10GE (not supported on Supervisor Engine 6-E and later)
TDR detects a cable fault by sending a signal along its wires and depending on the reflected signal it can
determine roughly where a cable fault could be. The variations on how TDR signal is reflected back
determine the results on TDR. On cat4k products, we only support cable fault types: OPEN or SHORT.
We do display Terminated status in case cable is proper terminated and this is done for illustrative
purpose.
Running the TDR Test
To start the TDR test, perform this task:
This example shows how to start the TDR test on port 1 on module 2:
Switch# test cable-diagnostics tdr int gi2/1
Switch#
This example shows the message that displays when the TDR test is not supported on a module:
Switch# test cable-diagnostics tdr int gi2/1
00:03:15:%C4K_IOSDIAGMAN-4-TESTNOTSUPPORTEDONMODULE: Online cable
diag tdr test is not supported on this module
Switch#
This example shows how to display TDR test results for a port:
Switch# show cable-diagnostics tdr interface gi4/13
Interface Speed Local pair Cable length Remote channel Status
Gi4/13 0Mbps 1-2 102 +-2m Unknown Fault
3-6 100 +-2m Unknown Fault
4-5 102 +-2m Unknown Fault
7-8 102 +-2m Unknown Fault
Command Purpose
Step 1
Switch# test cable-diagnostics tdr
{interface {interface interface-number}}
Starts the TDR test.
Step 2
Switch# show cable-diagnostics tdr
{interface {interface interface-number}}
Displays the TDR test counter information.