Shared Medium in CSMA CD Networks | Generated by AI
Question: What does the term “Multiple Access” mean in the context of CSMA/CD?
Answer:
Meaning of “Multiple Access” in CSMA/CD
In the acronym CSMA/CD (Carrier Sense Multiple Access with Collision Detection), the term Multiple Access refers to the network topology and usage model where multiple nodes (computers, printers, etc.) share the same single communication channel or transmission medium.
Here is a detailed breakdown of what this implies:
- Shared Medium: Unlike point-to-point connections where two devices have a dedicated wire between them, a “Multiple Access” network (such as traditional Ethernet using a coaxial cable or a hub) connects many devices to one common bus. All devices are physically connected to the same wire.
- Equal Rights: The term “Access” implies that every node on the network has an equal right to attempt to transmit data onto the shared medium. There is no central controller (like a master station) that explicitly grants permission to specific nodes to speak in a fixed order (which would be “controlled access”).
- The Need for Coordination: Because multiple devices have access to the same line simultaneously, if two or more decide to transmit at the exact same time, their signals will overlap and corrupt each other. This phenomenon is called a collision.
- Relation to the Protocol: The “Multiple Access” nature is precisely why the other parts of CSMA/CD are necessary:
- Carrier Sense (CS) is needed because everyone shares the line; you must check if someone else is using it.
- Collision Detection (CD) is needed because multiple people can access the line at once, leading to potential conflicts.
Summary: “Multiple Access” simply describes the scenario where many users compete for the use of a single shared communication path, necessitating a protocol to manage how they take turns speaking to avoid data collisions.
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