CSMA/CD LastModified: Monday, February 28, 2005
Short for Carrier Sense Multiple Access / Collision Detection, a set of rules determining how network devices respond when two devices attempt to use a data channel simultaneously (called a collision). Standard Ethernet networks use CSMA/CD to physically monitor the traffic on the line at participating stations. If no transmission is taking place at the time, the particular station can transmit. If two stations attempt to transmit simultaneously, this causes a collision, which is detected by all participating stations. After a random time interval, the stations that collided attempt to transmit again. If another collision occurs, the time intervals from which the random waiting time is selected are increased step by step. This is known as exponential back off. CSMA/CD is a type of contention protocol.  Networks using the CSMA/CD procedure are simple to implement but do not have deterministic transmission characteristics. The CSMA/CD method is internationally standardized in IEEE 802.3 and ISO 8802.3.
Ethernet and CSMA/CD This article describes how and why CSMA/CD works on an Ethernet network, and how it can fail. Introduction to CSMA/CD Contains a historical overview of CSMA/CD.	related categories: Ethernet Networks related terms: 100Base-T 802.11 collision collision detection collision domain contention Ethernet packet collision packet collision rate Shopping CSMA CD Products Compare Products,Prices and Stores Shop by Category: Wireless Access Points 262 Model Matches Networking Hubs and Switches 937 Model Matches