LAN Communication
A LAN is similar to a telephone system with one party line-not everyone can talk at the same time. The difference is that, with a LAN, the speed is so fast that it fosters the perception that many transactions are taking place at the same time. But just like a one-lane road, the heavier the traffic, the slower it moves.
Ethernet
Ethernet uses a system known as carrier sense multiple access with collision detection (CSMA/CD). It also uses the bus topology discussed earlier in this lesson. The term "carrier sense" means that the network card listens to the cable for a quiet period during which it can send messages. "Multiple access" refers to the fact that more than one computer can be connected to the same cable. And "collision detection" is the ability to detect whether messages have collided in transit (in which case neither message will arrive at its destination and both will be retransmitted).
Fast Ethernet was developed to meet the increasing demands on networks. Fast Ethernet works on the same principals as the original Ethernet, but operates at 10 times the speed. Ethernet transmits at 10 Mbps, and Fast Ethernet transmits at 100 Mbps.
Token Ring
As described earlier, a token ring network uses a "token" as the basis for deciding who can communicate on the network. Token rings transmit at 4 or 16 Mbps.