Ethernet Hubs Explained Segment 2 of 3 (Diagnostic Lights)
There’s no standard for these diagnostic lights. Every vendor uses different colors, different blink patterns, and different combinations of multiple lights to indicate different conditions. In general, though, there will be some more-or-less obvious indication when you have a wire that’s properly connected at both ends. Most vendors use a steady “on” light, to indicate that the wire is properly connected at both ends and that’s usually what they call a “link light.” A lot of vendors use some kind of a blinking or flashing indication to indicate that data is being passed actively on an interface. About the only thing all these indicators have in common is that for any interface, all of the associated lights are completely off that probably means something is fatally wrong or that no wire is properly connected.