On Fri, May 23, 2014 at 2:40 PM, Bourque Daniel <[email protected]> wrote: > 10 Mbs Full Duplex link can go very far... I test it for fun with a 300 > meters years ago.. No error for a weekend streaming a radio-station...
FYI: The 100 meter length limit for Ethernet derives from the time it takes for the jam signal to propagate through the medium after a collision is detected[1]. The jam signal has to be on the bus long enough for all sending nodes to detect it. If the length is too long, a sender might finish sending before the jam signal arrives. That's called a "late collision". The sender can't retransmit in that event, so the frame is lost. But on a full-duplex link, there are no collisions. So what's the next limiting factor? Attenuation? Skew? Crosstalk? Well, the IEEE spec doesn't say. It just says "thou shalt not exceed 100 meters". So you're in uncharted territory. As noted, much longer lengths will often work. I've heard claims of 300+ meters before, and personally seen ~380 feet in production. But you're on your own as far as performance and reliability goes. It may work fine, or demons may fly out of your nose[2]. -- Ben [1] http://en.wikipedia.org/wiki/CSMA/CD [2] http://www.catb.org/jargon/html/N/nasal-demons.html
