In computer networking, Carrier Sense Multiple Access With Collision Detection (CSMA/CD) is a network control protocol in which A computer network is a system for communication between computers. ... In the field of telecommunications, a communications protocol is the set of standard rules for data representation, signalling, authentication, and error detection required to send information over a communications channel. ...

• a carrier sensing scheme is used and
• a transmitting data station that detects another signal while transmitting a frame, stops transmitting that frame, transmits a jam signal, and then waits for a random time interval (known as "backoff delay" and determined using the truncated binary exponential backoff algorithm) before trying to send that frame again.

CSMA/CD is a modification of pure Carrier Sense Multiple Access (CSMA). Please visit this article for a complete description of the basic protocol. A carrier wave, or carrier is a waveform (usually sinusoidal) that is modulated (modified) to represent the information to be transmitted. ... Data is the plural of datum. ... In communications, transmission is the act of transmitting electrical messages (and the associated phenonomena of radiant energy that pass through media). ... In telecommunications, a frame is a packet which has been encoded for transmission over a particular link. ... In telecommunication, a jam signal is a signal that carries a bit pattern sent by a data station to inform the other stations that they must not transmit. ... A pocket watch. ... Truncated binary exponential backoff: In carrier sense multiple access with collision avoidance (CSMA/CA) networks and in carrier sense multiple access with collision detection (CSMA/CD, the channel access method used, for instance, in Ethernet) networks, the algorithm used to schedule retransmission after a collision such that the retransmission is... Carrier Sense Multiple Access (CSMA) is a non-deterministic Media Access Control (MAC) protocol in which a node verifies the absence of other traffic before transmitting on a shared physical medium, such as an electrical bus, or a band of electromagnetic spectrum. ...

Collision detection is used to improve CSMA performance by terminating transmission as soon as a collision is detected, and reducing the probability of a second collision on retry.

Methods for collision detection are media dependent, but on an electrical bus such as Ethernet, collisions can be detected by comparing transmitted data with received data. If they differ, another transmitter is overlaying the first transmitter's signal (a collision), and transmission terminates immediately. A jam signal is sent which will cause all transmitters to back off by random intervals, reducing the probability of a collision when the first retry is attempted. CSMA/CD is a layer 2 protocol in the OSI model.

Ethernet is the classic CSMA/CD protocol. Ethernet is a frame-based computer networking technology for local area networks (LANs). ...

See also the similar Carrier sense multiple access with collision avoidance (CSMA/CA) protocol. In computer networking, Carrier Sense Multiple Access With Collision Avoidance (CSMA/CA) is a network control protocol in which: a carrier sensing scheme is used, a data station that intends to transmit sends a jam signal after waiting a sufficient time for all stations to receive the jam signal, the...

Very partly derived from Federal Standard 1037C Federal Standard 1037C entitled Telecommunications: Glossary of Telecommunication Terms is a U.S. Federal Standard, issued by the General Services Administration pursuant to the Federal Property and Administrative Services Act of 1949, as amended. ...

References

IEEE802.3 CSMA/CD