Posted by: Yasir Irfan
Cisco, Cisco 3560, Cisco 3560-E, Cisco 3750-E, Cisco Learning, Cisco Tips, IOS commands, Layer 1 issues, Network Troubleshooting, Switches
Here is a simple and cool tool for solving layer 1 UTP cable issues in a Cisco Catalyst Switches, the command used for this function is “test cable-diagnostics tdr interface”
Here is the example
MBGF-DAC-3560-AS01#test cable-diagnostics tdr interface gigabitEthernet 0/1
TDR test started on interface Gi0/1
A TDR test can take a few seconds to run on an interface
Use ‘show cable-diagnostics tdr’ to read the TDR results.
The Catalyst 2960, 2970, 3560/3560-E, and 3750/3750-E switches have an integrated Time Domain Reflector (TDR), which is used to test cables associated with a port. TDR is supported only on 10/100/1000 and some 10/100 (Catalyst 2960) copper Ethernet ports. It is not supported on 10 GigabitEthernet or SFP module ports.
A TDR test can take a few seconds to run on an interface. Use “show cable-diagnostics tdr” to read the TDR results.
MBGF-DAC-3560-AS01#sho cable-diagnostics tdr interface gigabitEthernet 0/1
TDR test last run on: August 30 08:01:35
Interface Speed Local pair Pair length Remote pair Pair status
——— —– ———- —————— ———– ——————–
Gi0/1 1000M Pair A 54 +/- 4 meters Pair A Normal
Pair B 52 +/- 4 meters Pair B Normal
Pair C 53 +/- 4 meters Pair C Normal
Pair D 54 +/- 4 meters Pair D Normal