Cisco 7604 User Manual

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Cisco 7600 Series Router Cisco IOS Software Configuration Guide, Release 12.2SX
OL-4266-08
Chapter 9 Configuring Interfaces
Checking the Cable Status Using the TDR
*Sep 30 08:33:47: %LINK-5-CHANGED: Interface FastEthernet5/5, changed state to
administratively down
This example shows how to reenable Fast Ethernet port 5/5:
Router(config-if)# no shutdown
Router(config-if)#
*Sep 30 08:36:00: %LINK-3-UPDOWN: Interface FastEthernet5/5, changed state to up
To check if an interface is disabled, enter the EXEC show interfaces command. An interface that has
been shut down is shown as administratively down in the show interfaces command display.
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 router, 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 12.2SX on the Supervisor Engine 720,
Supervisor Engine 32, and Supervisor Engine 2 for information about which modules support the
TDR.
To start or stop the TDR test, perform this task:
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 #
Tip For additional information (including configuration examples and troubleshooting information), see the
documents listed on this page:
http://www.cisco.com/en/US/products/hw/routers/ps368/tsd_products_support_series_home.html
Command Purpose
test cable-diagnostics tdr interface { interface
interface-number
}
Starts or stops the TDR test.

Cisco 7604 Specifications

General

Brand	Cisco
Model	7604
Category	Network Router
Language	English