mitting. If the host detects another signal on the wire, it sends out an
extended jam signal that causes all nodes on the segment to stop sending data
(think, busy signal). The nodes respond to that jam signal by waiting a while
before attempting to transmit again. Backoff algorithms determine when the
colliding stations can retransmit. If collisions keep occurring after 15 tries,
the nodes attempting to transmit will then time out. Pretty clean!
one wire pair with a digital signal running in both directions on the wire. It
also uses the CSMA/CD protocol to help prevent collisions and to permit
retransmitting if a collision does occur. If a hub is attached to a switch, it
must operate in half-duplex mode because the end stations must be able to
detect collisions. Half-duplex Ethernet--typically 10BaseT--is only about
30 to 40 percent efficient as Cisco sees it, because a large 10BaseT network
will usually only give you 3- to 4Mbps--at most.
the transmitter of the transmitting device and the receiver of the receiving
device. There are no collisions to worry about because now it's like a freeway
with multiple lanes instead of the single-lane road provided by half duplex.
Full-duplex Ethernet is supposed to offer 100 percent efficiency in both
directions, e.g., you can get 20Mbps with a 10Mbps Ethernet running full
duplex, or 200Mbps for FastEthernet--woohoo! But this rate is something