Link Light means what?

What does a link light on a router mean? Does it mean that the router
and NIC both have power? More than that?

I had a link on a router, but could not ping the router from the PC. I
switched ports, and got communication.

Do I know if the port was bad or is it possible this is a coincidence?
Can a port be intermittently bad, while still providing a link light
also?

3com software says the NIC is working properly. (?)

John

 

Depending on the unit ( what router type and model do you own ? ) , a lit
LED can mean that either
the interface itself is up and operational, OR that L3 connectivity is
established. In either case one
should see the manual of the router. Many manufacturers handle it different.
In your case I suggest
that the hardware logic of the Interface was up, but no line protocol was
available so you were
unable to ping.

 

The Cisco 1600 I have sitting next to me give a link light for layer one
connectivity. I know this because I just plugged an ethernet loop back
cable in and it stayed lit (no flashing or anything).

I suspect others may be similar, "If I get a 'signal' on RX then I must have
a link to something."

-Jeff C