Cisco WS-SUP32-GE-3B Software Configuration Guide - Page 125

Chapter 7 Configuring Interfaces Checking the Cable Status Using the TDR Checking the Cable Status Using the TDR You can check the status of copper cables using the time domain reflectometer (TDR). The TDR detects a cable fault by sending a signal through the cable and reading the signal that is reflected back to it. All or part of the signal can be reflected back by any number of cable defects or by the end of the cable itself. Use the TDR to determine if the cabling is at fault if you cannot establish a link. This test is especially important when replacing an existing switch, upgrading to Gigabit Ethernet, or installing new cables. The port must be up before running the TDR test. If the port is down, you cannot enter the test cable-diagnostics tdr command successfully, and the following message is displayed: Router# test cable-diagnostics tdr interface gigabitethernet2/12 % Interface Gi2/12 is administratively down % Use 'no shutdown' to enable interface before TDR test start. Note • TDR can test cables up to a maximum length of 115 meters. • See the Release Notes for Cisco IOS Release 12.2ZY on the Supervisor Engine 32 PISA for information about which modules support the TDR. To start or stop the TDR test, perform this task: Command test cable-diagnostics tdr interface {interface interface-number} Purpose Starts or stops the TDR test. This example shows how to run the TDR-cable diagnostics: Router # test cable-diagnostics tdr interface gigabitethernet2/1 TDR test started on interface Gi2/1 A TDR test can take a few seconds to run on an interface Use 'show cable-diagnostics tdr' to read the TDR results. Router # OL-11439-03 Catalyst Supervisor Engine 32 PISA Cisco IOS Software Configuration Guide, Release 12.2ZY 7-19