4 ms·
The author kinda bungles his analogy/explanation of collision avoidance and detection. Wireless networks don't use CSMA/CD. They use CSMA/CA. There's a huge dif
by scurvy 10y ago
The author kinda bungles his analogy/explanation of collision avoidance and detection. Wireless networks don't use CSMA/CD. They use CSMA/CA. There's a huge difference, and it's one big reason why wireless throughput won't ever come close to PHY speed.
Wired ethernet uses CSMA/CD and it's one of the reasons it won the LAN networking wars of the 80's and 90's.
- dboreham 10y agoDo today's wired networks (1G+/FD/Cat6/fiber) still use CSMA/CD? I was under the impression that they don't.
- hchenji 10y agoNo, since wired networks are full duplex and are their own collision domains. No need to do carrier sensing at all.
- scurvy 10y agoNot entirely true. You can run half duplex gigabit connections on hubs. Not sure why you would, but you can. IEEE 802.3 covers all Ethernet standards and it still lists CSMA/CD. Largely for historical purposes, but it is in the spec. Starting with 10gig, full duplex is required so that was the first IEEE speed that did away with CSMA/CD.
- scurvy 10y agoSwitched networks are full duplex, point-to-point links, so there's no possibility of a collision from the transmitting station. That said, 802.3 still mentions CSMA/CD for half-duplex backward compatibility. Everything 10gig and above requires full duplex though.