Knowledge Checks

Channel partitioning protocols.

Which of the following statements is true about channel partitioning protocols?

Channel partitioning protocol can achieve 100% utilization, in the case that there is only one node that always has frames to send

Channel partitioning protocols can achieve 100% channel utilization, in the case that all nodes always have frames to send.

There can be times when the channel is idle, when a node has a frame to send, but is prevented from doing so by the medium access protocol.

There can be simultaneous transmissions resulting in collisions.

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1/7

Pure Aloha and CSMA.

Which of the following statements is true about both Pure Aloha, and CSMA (both with and without collision detection?

Pure Aloha and CSMA can achieve 100% utilization, in the case that there is only one node that always has frames to send

There can be times when the channel is idle, when a node has a frame to send, but is prevented from doing so by the medium access protocol.

Pure Aloha and CSMA can achieve 100% channel utilization, in the case that all nodes always have frames to send.

There can be simultaneous transmissions resulting in collisions.

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2/7

Polling and token-passing protocols.

Which of the following statements is true about polling and token-passing protocols?

These protocol can achieve close to 100% channel utilization, in the case that all nodes always have frames to send (the fact that the utilization is close to, but not exactly, 100% is due to a small amount of medium access overhead but not due to collisions)

These protocol can achieve close 100% utilization, in the case that there is only one node that always has frames to send (the fact that the utilization is close to, but not exactly, 100% is due to a small amount of medium access overhead but not due to collisions)

There can be times when the channel is idle for more than a short period of time, when a node has a frame to send, but is prevented from doing so by the medium access protocol.

There can be simultaneous transmissions resulting in collisions.

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3/7

Characteristics of Multiple Access Protocols (a).

Consider the following multiple access protocols that we've studied: (1) TDMA, and FDMA (2) CSMA (3) Aloha, and (4) polling. Which of these protocols are collision-free (e.g., collisions will never happen)?

CSMA and CSMA/CD

Polling

TDMA and FDMA

Aloha

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4/7

Characteristics of Multiple Access Protocols (b).

Consider the following multiple access protocols that we've studied: (1) TDMA, and FDMA (2) CSMA (3) Aloha, and (4) polling. Which of these protocols requires some form of centralized control to mediate channel access?

Polling

Aloha

TDMA and FDMA

CSMA and CSMA/CD

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5/7

Characteristics of Multiple Access Protocols (c).

Consider the following multiple access protocols that we've studied: (1) TDMA, and FDMA (2) CSMA (3) Aloha, and (4) polling. For which of these protocols is the maximum channel utilization 1 (or very close to 1)?

CSMA and CSMA/CD

Polling

TDMA and FDMA

Aloha

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6/7

Characteristics of Multiple Access Protocols (d).

Consider the following multiple access protocols that we've studied: (1) TDMA, and FDMA (2) CSMA (3) Aloha, and (4) polling. For which of these protocols is there a maximum amount of time that a node knows that it will have to wait until it can successfully gain access to the channel?

Polling

Aloha

TDMA and FDMA

CSMA and CSMA/CD

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7/7

Knowledge checks

Channel partitioning protocols.

Pure Aloha and CSMA.

Polling and token-passing protocols.

Characteristics of Multiple Access Protocols (a).

Characteristics of Multiple Access Protocols (b).

Characteristics of Multiple Access Protocols (c).

Characteristics of Multiple Access Protocols (d).