|  | 1.2 | LANs
| 1.2.3 | Carrier sense multiple access with collision detection
On an Ethernet LAN, only one transmission is allowed at any given time. An Ethernet LAN is referred to as a Carrier Sense Multiple Access with Collision Detection (CSMA/CD) network. This means that one node's transmission traverses the entire network and is received and examined by every node. When the signal reaches the end of a segment, terminators absorb it to prevent it from going back onto the segment. When a station wishes to transmit a signal, it checks the network to determine whether another station is currently transmitting. If the network is not being used, the station proceeds with the transmission. While sending a signal, the station monitors the network to ensure that no other station is transmitting at that time. It is possible that two stations could both determine that the network is available and start transmitting at approximately the same time. If this should occur, they would cause a collision, as is illustrated in the upper part of the graphic. When a transmitting node recognizes a collision, it transmits a jam signal that causes the collision to last long enough for all other nodes to recognize it. All transmitting nodes would then stop sending frames for a randomly selected period of time before attempting to retransmit. If subsequent attempts also result in collisions, the node would try to retransmit as many as fifteen times before finally giving up. The clocks indicate various backoff timers. If the two timers are sufficiently different, one station would succeed the next time.