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Cisco ME 3400 EthernetAccess Switch SoftwareConfiguration Guide
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Chapter36 Troubleshooting Using TDR
To end a trace in progress, enter the escape sequence (Ctrl-^ X by default). Simultaneously press and
release the Ctrl, Shift, and 6 keys, and then press the X key.
Using TDR
These sections contain this information:
•Understanding TDR, page 36-17
•Running TDR and Displaying the Results, page 36-17

Understanding TDR

You can use the Time Domain Reflector (TDR) feature to diagnose and resolve cabling problems. When
running TDR, a local device sends a signal through a cable and compare s the reflecte d signal to the initi al
signal.
TDR is supported only on the copper Ethernet 10/100 port s o n the Ci sco ME swi tch .
TDR can detect these cabling problems:
•Open, broken, or cut twisted-pair wires—The wires are not connected to the wires from the remote
device.
•Shorted twisted-pair wires—The wires are touching each other or the wires from the rem ote device.
For example, a shorted twisted pair can occur if one wire of the twisted pair is soldered to the other
wire.
If one of the twisted-pair wires is open, TDR can find the length at which the wire is open.
Use TDR to diagnose and resolve cabling problems in these situations:
•Replacing a switch
•Setting up a wiring closet
•Troubleshooting a connection between two devices when a link cannot be established or when it is
not operating properly

Running TDR and Displaying the Results

To run TDR , ent er th e test cable-diagnostics tdr interface interface-id privileged EXEC command:
To display the results, enter the show cable-diagnostics tdr interface interface-id privileged EXEC
command. For a description of the fields in the display, see the command reference for this release.
Note TDR is supported only on the copper Ethernet 10/100 ports on the Cisco ME switch.