The " DIX-group " with Gary Robinson ( DEC ), Phil Arst ( Intel ), and Bob Printis ( Xerox ) submitted the so-called " Blue Book " CSMA / CD specification as a candidate for the LAN specification.

In addition to CSMA / CD, Token Ring ( supported by IBM ) and Token Bus ( selected and henceforward supported by General Motors ) were also considered as candidates for a LAN standard.

As early as March 1982 ECMA TC24 with its corporate members reached agreement on a standard for CSMA / CD based on the IEEE 802 draft.

Because the DIX proposal was most technically complete and because of the speedy action taken by ECMA which decisively contributed to the conciliation of opinions within IEEE, the IEEE 802. 3 CSMA / CD standard was approved in December 1982.

* CSMA / CD and CSMA / CA " backoff " waiting time and frame retransmissions after detected collisions.

One faction wanted to keep CSMA / CD in order to keep it pure Ethernet, even though the collision domain problem limited the distances to one tenth that of 10BASE-T. Another faction wanted to change to a polling architecture from the hub ( they called it " Demand Priority Protocol ") in order to maintain the 10baseT distances, and also to make it a deterministic protocol.

When Ethernet became Fast Ethernet, it continued to use the Carrier Sense Multiple Access With Collision Detection ( CSMA / CD ) mechanism to manage traffic on the network cable.

Carrier sense multiple access with collision avoidance ( CSMA / CA ) in computer networking, is a network multiple access method in which carrier sensing is used, but nodes attempt to avoid collisions by transmitting only when the channel is sensed to be " idle ".

It is particularly important for wireless networks, where the collision detection of the alternative CSMA / CD method is not possible for technical reasons.

Simplified Algorithm of CSMA / CA

Although CSMA / CA has been used in a variety of wired communication systems, it is particularly beneficial in a wireless LAN due to a common problem of multiple stations being able to see the Access Point, but not each other.

CSMA / CA can optionally be supplemented by the exchange of a Request to Send ( RTS ) packet sent by the sender S, and a Clear to Send ( CTS ) packet sent by the intended receiver R. Thus alerting all nodes within range of the sender, receiver or both, to not transmit for the duration of the main transmission.

CSMA / CA performance is based largely upon the modulation technique used to transmit the data between nodes.

Studies show that under ideal propagation conditions ( simulations ), Direct Sequence Spread Spectrum ( DSSS ) provides the highest throughput for all nodes on a network when used in conjunction with CSMA / CA and the IEEE 802. 11 RTS / CTS exchange under light network load conditions.

* Apple's LocalTalk implemented CSMA / CA on an electrical bus using a three-byte jamming signal.

* IEEE 802. 15. 4 ( Wireless PAN ) uses CSMA / CA

* The ITU-T G. hn standard, which provides a way to create a high-speed ( up to 1 Gigabit / s ) local area network using existing home wiring ( power lines, phone lines and coaxial cables ), uses CSMA / CA as a channel access method for flows that don't require guaranteed quality of service, specifically the CSMA / CARP variant.

* CSMA / CA RTS / CTS Simulation

tr: CSMA / CA

ca: CSMA / CA

cs: CSMA / CA

da: CSMA / CA

eu: CSMA / CA

it: CSMA / CA

he: Carrier sense multiple access # CSMA / CA

nl: CSMA / CA

ja: CSMA / CA

pl: CSMA / CA

pt: CSMA / CA

Collision avoidance is used to improve the performance of the CSMA method by attempting to divide the channel somewhat equally among all transmitting nodes within the collision domain.

Carrier sense multiple access with collision detection ( CSMA / CD ) is a Media Access Control method in which:

CSMA / CD is a modification of pure carrier sense multiple access ( CSMA ).

CSMA / CD is used to improve CSMA performance by terminating transmission as soon as a collision is detected, thus shortening the time required before a retry can be attempted.

Modern Ethernet networks built with switches and full-duplex connections no longer utilize CSMA / CD though it is still supported for backwards compatibility.

Carrier Sense Multiple Access ( CSMA ) is a probabilistic Media Access Control ( MAC ) protocol in which a node verifies the absence of other traffic before transmitting on a shared transmission medium, such as an electrical bus, or a band of the electromagnetic spectrum.

In other words, CSMA is based on the principle " sense before transmit " or " listen before talk ".

CSMA / CD 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.

In CSMA / CA collision avoidance is used to improve the performance of CSMA by attempting to be less " greedy " on the channel.

; Non-persistent: Non persistent CSMA is less aggressive compared to P persistent protocol.

Since bit errors are very rare in wired networks, Ethernet does not provide flow control or automatic repeat request ( ARQ ), meaning that incorrect packets are detected but only cancelled, not retransmitted ( except in case of collisions detected by the CSMA / CD MAC layer protocol ).

In wireless networks such as IEEE 802. 11, flow control and error management is part of the CSMA / CA MAC protocol, and not part of the LLC layer.

** Multiple access protocols for channel-access control, for example CSMA / CD protocols for collision detection and retransmission in Ethernet bus networks and hub networks, or the CSMA / CA protocol for collision avoidance in wireless networks.

The most widespread multiple access protocol is the contention based CSMA / CD protocol used in Ethernet networks.

However, the media access control ( the multiple access protocol ) is Dynamic TDMA in HiperLAN / 2, while CSMA / CA is used in 802. 11a.

Because wireless LANs use the CSMA / CA protocol, nodes will wait their

The physical medium is accessed through a CSMA / CA protocol.

The first offered singulation protocol is the ALOHA protocol, originally used decades ago in ALOHAnet and very similar to CSMA / CD used by Ethernet.