ITT300 Data Communication Chapter 7 Quiz
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Questions and Answers

What occurs in the 1-Persistent method when a station senses that the line is idle?

  • It waits a random time before transmitting.
  • It queues the frame for later transmission.
  • It transmits immediately. (correct)
  • It ignores the line.

    • In nonpersistent strategy, a station waits for the line to be idle before sensing it again.

    True

    List the three values of energy levels in a channel.

    Zero, Normal, Abnormal

    In the p-persistent method, the station senses the line continuously in relation to ______.

    <p>one persistent slot</p> Signup and view all the answers

    Which controlled access method involves one primary station and multiple secondary stations?

    <p>Polling</p> Signup and view all the answers

    All stations in controlled access can send their frames at any time.

    <p>False</p> Signup and view all the answers

    What is the main advantage of the p-persistent approach over nonpersistent and 1-persistent strategies?

    <p>It reduces the chance of collision and improves efficiency.</p> Signup and view all the answers

    Match the following persistence strategies with their description:

    <p>1-Persistent = Transmit immediately when idle Nonpersistent = Waits a random period if busy p-Persistent = Balances between immediate and wait strategies Controlled Access = Stations consult before sending</p> Signup and view all the answers

    What is the primary purpose of multiple-access methods in networking?

    <p>To coordinate access to a shared link</p> Signup and view all the answers

    In random access methods, one node has superior rights over others.

    <p>False</p> Signup and view all the answers

    What does CSMA stand for in networking protocols?

    <p>Carrier Sense Multiple Access</p> Signup and view all the answers

    The strategy where a station sends its frame immediately if the line is idle is called _______.

    <p>1-Persistent</p> Signup and view all the answers

    Which of the following strategies does CSMA NOT include?

    <p>2-Persistent</p> Signup and view all the answers

    CSMA can completely eliminate the possibility of a collision.

    <p>False</p> Signup and view all the answers

    What is the key action that stations take before transmitting in the CSMA method?

    <p>Listen to the medium</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>p-Persistent = Sends with a probability after sensing idle CSMA = Carrier Sense Multiple Access 1-Persistent = Sends frame immediately if idle Nonpersistent = Waits for idle and then waits again if busy</p> Signup and view all the answers

    What is the function of the Select Mode in polling access method?

    <p>Used whenever the primary device has data to send</p> Signup and view all the answers

    In token passing method, each station has both a predecessor and a successor.

    <p>True</p> Signup and view all the answers

    What is the primary device responsible for in data exchanges?

    <p>Controlling the link and managing data exchanges</p> Signup and view all the answers

    In CSMA, the method that immediately transmits if the line is idle is called _____ persistent.

    <p>1</p> Signup and view all the answers

    Match the following methods with their descriptions:

    <p>CSMA = Minimizes but cannot eliminate collisions Polling = Primary device controls the data exchange Token Passing = Stations organized in a logical ring Controlled Access = Stations coordinate to gain sending rights</p> Signup and view all the answers

    Which of the following is NOT a strategy of CSMA?

    <p>5-Persistent</p> Signup and view all the answers

    In the Poll Mode, the primary device sends data to the secondary device.

    <p>False</p> Signup and view all the answers

    What happens to a token after a station finishes sending frames?

    <p>The station releases the token for use by the successor.</p> Signup and view all the answers

    Study Notes

    Introduction to Access Methods

    • Nodes connected via a multipoint link experience challenges in access control to prevent packet collisions.
    • Access methods or protocols coordinate access to the shared medium.

    Multiple Access Methods

    • Multiple access methods are necessary for efficient link usage among connected nodes.

    Random Access Methods

    • All nodes have equal access rights with no superior control.
    • Carrier Sense Multiple Access (CSMA) is a key random access method designed to minimize collision chances.
    • CSMA operates on the principle of "listen before talk," where stations check the medium before transmitting.
    • Although CSMA reduces collision risks, it cannot completely eliminate them.

    CSMA Strategies

    • 1-Persistent Strategy:
      • If the line is idle, the station transmits immediately, risking collisions due to simultaneous transmissions.
    • Nonpersistent Strategy:
      • If the line is busy, the station waits a random time before re-sensing, which lowers collision chances but can reduce overall efficiency.
    • p-Persistent Strategy:
      • Combines benefits of other strategies, allowing stations to wait a set probability before transmitting to balance efficiency and collision risk.

    CSMA/CD (Collision Detection)

    • Monitors energy levels to detect collisions:
      • Zero: Channel is idle
      • Normal: Station is successfully sending data
      • Abnormal: Collision detected with energy readings exceeding normal levels.

    Controlled Access Methods

    • Stations must consult to determine which has the right to send data, preventing unauthorized transmissions.
    • Key controlled access methods include reservation, polling, and token passing.

    Polling

    • Centralized method where one primary station controls communication with secondary stations.
    • Select Mode: Primary sends data to a secondary station.
    • Poll Mode: Primary station requests data from secondary stations.

    Token Passing

    • Stations are arranged in a logical ring where each has a predecessor and successor.
    • A special packet called a token circulates; a station must wait for the token to transmit data.
    • After transmission, the token is released for the next station, ensuring orderly access to the medium.

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    Related Documents

    ITT300 - CHAPTER 7 ACCESS CONTROL.pdf

    Description

    Test your knowledge on access methods in data communication with this quiz based on Chapter 7 of Behrouz A. Forouzan's material. Understand how node access control works in multipoint bus topology environments and prevent packet collisions. Challenge yourself and deepen your understanding of networking concepts.

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