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Cisco Meraki Documentation

Using the Cable Test Live tool

Cisco Meraki MS switches have per-port cable testing capabilities, which utilize TDR functions to detect faults in metallic cables by sending and observing the responses of electrical pulses. This can be used to eliminate common layer 1 cabling issues by outputting the cable length and testing the status of each cable pair.

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Make sure the cable is connected to devices at both ends, before running this test. 

Use of this test can disrupt traffic on 10 or 100 Mbps links - gigabit links will not be affected.

This tool is intended for testing copper twisted-pair cabling as designated under the ANSI/TIA-568 cabling standard. It is not intended for use with fiber-optic cabling, as this requires the use of Digital Optical Monitoring, which the MS platform does not support.

To perform a cable test using Dashboard, navigate to Monitor > Switches > choose a switch > Tools. Then, scroll to the "Cable Test" tool section. Next, enter the port or port range (ie. "1" or "1-24" without quotes) into the test window and click the Run cable test button.


Once the Run cable test button is clicked, you can receive one of several test result outputs:



Good cable and good pair


Unused or terminated pair


The impedance* is not within the expected bounds, either too high or too low


Specified pair too strongly coupled to pair X, indicating a high amount of crosstalk

*Proper termination of Cat5/6 cable requires a 100Ω differential impedance between the positive and negative cable terminals. The IEEE 802.3 allows for a termination of as high as 115 Ω or as low as 85 Ω. If the termination falls outside of this range, it is reported by the cable diagnostics as an anomalous termination.


Example of a cable test output: 



The cable test will also output which pair is open if you have an open pair on your Ethernet cable. The diagram below illustrates how the pairs are numbered in a T568B straight through cable RJ-45 pinout.



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