CSMA/CD, CSMA/CA, or Both?

About this interactive

From the lesson: - **Both:** carrier sense (listen, and send only when nobody else is talking) and multiple access (many devices share the medium). After a collision, each device runs the backoff algorithm: it waits a random time, so the two usually pick different times. - **CSMA/CD (collision detection):** while sending, the device watches for a collision; if it senses one it stops right away and backs off. Used on wired Ethernet, especially with a hub. On a switch every port is its own collision domain and runs full duplex, so CD is rarely needed. - **CSMA/CA (collision avoidance):** tries to avoid the collision in the first place, for example by announcing its intent to send before the data. Wireless uses it, because an access point is half duplex: one device at a time.

What you'll learn

Tell CSMA/CD (detect a collision while sending, stop, back off) from CSMA/CA (try to avoid the collision before sending)
Recognize what the two share: carrier sense, multiple access and a random backoff after a collision
Place CSMA/CD in wired, hub-based Ethernet and CSMA/CA in half-duplex wireless networks

Aligned to

CompTIA Network+

1.1 Explain concepts related to the Open Systems Interconnection (OSI) reference model.

Cisco CCNA

1.3 Compare physical interface and cabling types

Key terms

Carrier Sense Multiple Access with Collision Detection: The media access control method used in traditional Ethernet where devices listen before transmitting and detect collisions if two devices transmit simultaneously, then retransmit after a random backoff period. CSMA/CD is defined for half-duplex Ethernet and is not used in full-duplex switched networks.
Carrier Sense Multiple Access with Collision Avoidance: A network access method used in wireless half-duplex environments where devices listen before transmitting and announce intent to transmit in order to avoid collisions before they occur.
Backoff Algorithm: A procedure used after a collision is detected in which each device waits a random amount of time before attempting to retransmit, reducing the likelihood of repeated collisions.
Half Duplex: A communication mode that allows data to be transmitted in both directions but only one direction at a time.
Collision Domain: A network segment where data packets can collide with each other when transmitted simultaneously.
Wireless Access Point: A device that allows wireless devices to connect to a wired network using Wi-Fi.

Topics

Csma Cd Csma Ca Backoff Collisions Wireless Interactive Categorize

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