This cable tester has numbered fobs that plug in the other end of an Ethernet port and report back which number they are;

If the cable tester is accidentally plugged into a switch port when the test is sent; will it just be a dropped packet; or will it cause hardware damage?

  • 1
    Methods differ, there's no standard for that. Usually I'd say those things are designed with a bit of common sense but you should really consult the manual.
    – Zac67
    Jan 25 at 20:01
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    I'm not familiar with that unit, but I would assume Klein would build a tester that can sense a live line. (with LLDP/CDP enabled, it could tell you the switch, and port.)
    – Ricky
    Jan 25 at 23:33

1 Answer 1


From the linked shop:

HUB BLINK MODE: Hub blink mode enables the identification of port locations on a hub or switch, facilitating efficient network management

That pretty much guarantees that plugging into a live switch port is a normal mode of testing and nothing breaks. They even show that test in the video.

  • 1
    From the manual: Do not initiate HUB BLINK MODE on a PoE Port.
    – leeand00
    Jan 29 at 17:24
  • Does the voltage warning tell you that it is a PoE Port and that you should not run the HUB BLINK MODE ?
    – leeand00
    Jan 29 at 18:25

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