11

I just noticed (in fact a non-technical colleague of mine told me) that there are 2 LEDs on a RJ45 connector. I always thought there was only 1.

Could somebody tell me what they're for? I'm pretty sure that the one on the right that flashes all the time indicates traffic but what about the left one?

Thanks,

Improve this question

2 Answers 2

Reset to default
14

One of the LEDs is typically an "activity" indicator, so it will flash whenever data is being transmitted.

The other LED is usually a "line speed" indicator and is typically orange for 10Mbit and green for 100Mbit line speeds. There may be another convention for gigabit speeds or full/half duplex but they will depend on the manufacturer.

Improve this answer
1
  • 5
    3 years later this seems more appropriate for line speed indicator: no color = 10mbps, orange = 100mpbs, green = gigabit.
    – Ev Dolzhenko
    Jul 20, 2014 at 9:34
7

RJ45 connectors are used in telephony, and the connectors used for Ethernet are more correctly referred to using the generic name 8P8C, although calling them RJ45 connectors is much more common.

They also do not always have LEDs. When there are two one commonly flashes when there is 100mbit connectivity and one for 1Gbit, or one for connection and one for data, or different combinations of those. It depends on the manufacturer.

Improve this answer
1
  • 2
    telephony connector are RJ11 in France, not RJ45.
    – m-ric
    Jul 21, 2016 at 14:17

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .