About this interactive
The lesson's two ways to control access to a half-duplex medium:
- **Controlled:** each machine is given its turn, or time slot, to speak, perhaps by an orchestrator. Only one device sends at a time, so collisions never happen. Token Ring passes the right to speak from machine to machine. The drawback: many machines have nothing to say when their turn comes.
- **Contention-based:** any machine may talk at any time. Collisions can happen, and the method deals with them. CSMA/CD (collision detection) and CSMA/CA (collision avoidance) are both contention-based.
What you'll learn
- Decide whether a media access method is controlled (each device gets a turn, so collisions cannot happen) or contention-based (any device may send, and collisions are dealt with)
- Recognize token passing as controlled access and CSMA/CD and CSMA/CA as contention-based access
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
- Controlled Access
- A media access method that assigns each device a designated time slot to transmit, preventing collisions by ensuring only one device speaks at a time.
- Contention-Based Access
- A media access method that allows any device to transmit at any time, relying on collision detection or avoidance mechanisms to handle simultaneous transmissions.
- Media Access Control
MAC
- A sublayer of the Data Link layer that controls how devices on a network gain access to a medium and transmit data.
- 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.
Topics
Media Access Control
Controlled Access
Contention Based Access
Collisions
Interactive
Streak Sort
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