How to Use the Cable Test Live Tool
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Overview
Cisco Meraki MS switches have per-port cable testing capabilities that use TDR functions to detect faults in metallic cables by sending electrical pulses and observing the responses. The tool eliminates common Layer 1 cabling issues by outputting the cable length and testing the status of each cable pair.
This tool tests copper twisted-pair cabling designated under the ANSI/TIA-568 cabling standard. Do not use it with fiber-optic cabling, which requires Digital Optical Monitoring (DOM) instead.
DOM is supported on MS120, MS125, MS130, MS210, MS225, MS250, MS350, MS355, MS410, and MS425 switches running firmware MS 17 or higher. Refer to the Digital Optical Monitoring documentation for more details.
Learn more with this free online training course on the Meraki Learning Hub:
Prerequisites
- Copper twisted-pair cabling that conforms to the ANSI/TIA-568 standard
- The cable connected to devices at both ends before you run the test
Running this test may disrupt traffic on the port.
Step-by-step instructions
Run a cable test
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Go to Monitor > Switches, then choose a switch.
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Select the Tools tab.
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Scroll to the Cable Test tool section.
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Enter the port or port range in the test window — for example, 1 for a single port or 1-24 for a range.
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Select the Run cable test button.
Verification
After you select Run cable test, the tool returns a status result for each cable pair. A result of OK on the tested pairs confirms a good cable and a good pair.
Read the test result statuses
Each tested pair returns one of the following statuses:
- OK — Good cable and good pair.
- OPEN — Unused or terminated pair.
- ABNORMAL — The impedance* is not within the expected bounds, either too high or too low.
- COUPLEX — The specified pair is too strongly coupled to pair X, indicating a high amount of crosstalk.
*Proper termination of Cat5/6 cable requires a 100 Ω differential impedance between the positive and negative cable terminals. The IEEE 802.3 standard allows a termination as high as 115 Ω or as low as 85 Ω. If the termination falls outside this range, the cable diagnostics report it as an anomalous termination.
If your Ethernet cable has an open pair, the cable test also outputs which pair is open. The diagram below illustrates how the pairs are numbered in a T568B straight-through cable RJ-45 pinout.
