I’ve always wondered whether network interfaces that have these flashing lights flash as a gimmick or do they actually indicate the flow of traffic? Perhaps one flash per packet in or out? I wish I could remember what my call up modem looked like to make a historical comparison too.
TL-SG105E
I went down some kind of a rabbit hole. I looked up my motherboard’s NIC’s data sheet and… Dam it! Why is tech so interesting!?
Source: https://datasheet4u.com/pdf-down/R/T/L/RTL8125BG-CG-Realtek.pdf
Something to be wary of when interpreting the datasheet:
Bad wording on their part. What they really mean is: “LED blinking when Ethernet packets transmitted/received AND the link is currently in a XYZMbps link speed mode”. The mode is negotiated once after you plug a cable in and usually does not change after that, regardless of how much data you try to send.
Technically each linkspeed/mode is a whole ethernet standard of its own, but we mostly gloss over that and pretend to end users that they’re backwards compatible.
Very insightful! Are those the speeds that I can
catfrom/sys/class/net/[interface name]/speed? Assuming you know Linux, that is. Those negotiated speeds, are they hardcoded into the NIC and selected/negotiated based on what category cable I’m using and other such hardware related factors? Also, is there any “wiggle room”? As in, does it do a speed test to check the limits of the physical layer or does it just follow some vendor specifications?https://en.wikipedia.org/wiki/Autonegotiation
Noice