- The central activity of any networking system is the method of access to the transmission medium. Wireless systems use the access control methods of Ethernet, which is called Carrier Sense Multiple Access with Collision Detection, CSMA/CD. FDDI uses the token ring method.
- In CSMA/CD, Ethernet's Media Access Control procedures, all computers attached to the same cable receive data transmitted by one of the computers. The sender of data has to check for silence on the cable before sending data and then listens to see if any other computer starts transmitting while its transmission is in process. If another computer starts transmitting, the detecting computer sends a back off signal and all computer stop transmitting for a random period.
- In token ring networks, an empty data packet passes continually to each of the computers on the network. Any computer wishing to send data puts it's information in the empty packet and writes in the address of the intended recipient. The packet moves on to the next computer which passes the packet on to the next computer in the ring if the packet does not bear its address. If the packet is addressed to that computer, the recipient takes the data and wipes the packet bare. It either wipes out the address and passes on the blank packet to the next computer, or it fills the packet with data it wants to send and fills in the address of the recipient. All computer on the network receiver the data in turn and forward packets on if that data was not intended for that computer.
- The principal media for most Ethernet networks in the world is Unshielded Twisted Pair cable, although Ethernet standards are also published recommending fiber optic cable and twin axial cable. Token ring networks usually run over Shielded Twisted Pair cable, but can also be implemented with Unshielded Twisted Pair or fiber optic cable. FDDI stands for Fiber-distributed Data Interface and runs over fiber optic cable. Wireless networks transmit data over radio waves.
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