CSMA Protocols and Collision Vulnerability Quiz
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Questions and Answers

What is the purpose of the MAC (Medium Access Control) sublayer?

  • To assign control over another station
  • To coordinate transmission of active nodes (correct)
  • To handle error and flow control
  • To determine when a station can use the link

    • Which of the following is the main task of Multiple Access Protocols?

  • Coordinating transmission of active nodes
  • Minimizing collisions to utilize bandwidth (correct)
  • Assigning control over another station
  • Determining when a station can use the link

    • What is the definition of throughput?

  • The amount of time it takes for the signal to travel from sender to receiver
  • The amount of data moved successfully in a given time period (correct)
  • The time it takes for the head of the signal to travel from sender to receiver
  • The amount of data lost during transmission

    • What is the problem with multiple nodes transmitting at the same time on a shared link?

    <p>The link bandwidth is wasted during collision</p> Signup and view all the answers

    What is the purpose of Random Access (or contention) Protocols?

    <p>To minimize collisions and utilize bandwidth</p> Signup and view all the answers

    What is the role of the Link Layer Control (LLC) in the data link layer?

    <p>Responsible for error and flow control</p> Signup and view all the answers

    What is the purpose of Medium Access Control (MAC) Protocols?

    <p>To minimize collisions and utilize bandwidth</p> Signup and view all the answers

    Which method for controlled access provides in order access to a shared medium so that every station has a chance to transfer?

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

    Which access method in polling uses a primary station and secondary stations for data exchanges?

    <p>Centralized polling</p> Signup and view all the answers

    Which access method in polling does not have a primary and secondary station?

    <p>Distributed polling</p> Signup and view all the answers

    Which access method in polling can be done in order or based on a predetermined order?

    <p>Distributed polling</p> Signup and view all the answers

    Which network protocol uses a token to control access to the medium?

    <p>Token Passing</p> Signup and view all the answers

    Which multiple-access method divides the transmission medium into separate frequency bands?

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

    Which multiple-access method shares the bandwidth capacity in time between multiple stations?

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

    Which multiple-access method carries all transmissions simultaneously on one channel?

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

    Which multiple-access method assigns a transmission channel between a sender and a receiver for a certain amount of time?

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

    Which of the following statements is true about the ALOHA protocol?

    <p>ALOHA is a multiple access protocol</p> Signup and view all the answers

    What is the purpose of random retransmission time in the ALOHA scheme?

    <p>To reduce the likelihood of additional collisions between stations</p> Signup and view all the answers

    In the Pure ALOHA protocol, what is the time out equal to?

    <p>The maximum round-trip propagation delay</p> Signup and view all the answers

    Which of the following is true about Slotted ALOHA?

    <p>Time is divided into slots equal to a frame transmission time</p> Signup and view all the answers

    What is the maximum throughput in Pure ALOHA?

    <p>18%</p> Signup and view all the answers

    Which of the following is a disadvantage of ALOHA protocols?

    <p>Low channel utilization</p> Signup and view all the answers

    What is the purpose of carrier sense in the Carrier Sense Multiple Access (CSMA) protocol?

    <p>To reduce the possibility of collision</p> Signup and view all the answers

    Which protocol reduces the possibility of collisions like non-persistent and reduces channel idle time like 1-persistent?

    <p>p-persistent CSMA</p> Signup and view all the answers

    What should a station do in the 1-persistent CSMA protocol if the medium is busy?

    <p>Continuously listen until medium becomes idle</p> Signup and view all the answers

    What is the maximum number of stations (n) for which stability is ensured in p-persistent CSMA?

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

    Which CSMA protocol requires a station to wait a random amount of time (backoff) if the medium is busy?

    <p>Non-persistent CSMA</p> Signup and view all the answers

    What is the main advantage of using CSMA/CD over other CSMA protocols?

    <p>Ability to detect collisions</p> Signup and view all the answers

    What happens if a collision occurs during transmission in CSMA/CD?

    <p>All of the above</p> Signup and view all the answers

    Which protocol is widely used for bus topology LANs?

    <p>CSMA/CD</p> Signup and view all the answers

    Which of the following is true about the ALOHA protocol?

    <p>ALOHA protocol was developed in the early 1970s to connect computers situated on different Hawaiian islands.</p> Signup and view all the answers

    Which multiple-access method divides the transmission medium into separate frequency bands?

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

    Which multiple-access method carries all transmissions simultaneously on one channel?

    <p>CSMA/CA</p> Signup and view all the answers

    What is the purpose of the MAC (Medium Access Control) sublayer?

    <p>To control access to the medium and handle data link layer protocols.</p> Signup and view all the answers

    What is the maximum throughput in Pure ALOHA?

    <p>18%</p> Signup and view all the answers

    What is the purpose of random retransmission time in the ALOHA scheme?

    <p>To spread out the retransmission and reduce the likelihood of additional collisions between stations.</p> Signup and view all the answers

    What is the purpose of carrier sense in the Carrier Sense Multiple Access (CSMA) protocol?

    <p>To detect the presence of other transmissions.</p> Signup and view all the answers

    Which of the following is the purpose of the MAC (Medium Access Control) sublayer?

    <p>To minimize collisions and utilize the bandwidth</p> Signup and view all the answers

    What is the main advantage of using CSMA/CD over other CSMA protocols?

    <p>It reduces the possibility of collisions like non-persistent and reduces channel idle time like 1-persistent</p> Signup and view all the answers

    What is the maximum number of stations (n) for which stability is ensured in p-persistent CSMA?

    <p>n=2</p> Signup and view all the answers

    Which multiple-access method divides the transmission medium into separate frequency bands?

    <p>FDMA (Frequency Division Multiple Access)</p> Signup and view all the answers

    What is the purpose of carrier sense in the Carrier Sense Multiple Access (CSMA) protocol?

    <p>To determine when a station can use the link (medium)</p> Signup and view all the answers

    Which of the following is a disadvantage of ALOHA protocols?

    <p>High collision probability</p> Signup and view all the answers

    Which access method in polling can be done in order or based on a predetermined order?

    <p>Round Robin</p> Signup and view all the answers

    According to the text, which CSMA protocol reduces the possibility of collisions like non-persistent and reduces channel idle time like 1-persistent?

    <p>p-persistent CSMA</p> Signup and view all the answers

    According to the text, what is the maximum number of stations (n) for which stability is ensured in p-persistent CSMA?

    <p>n x p</p> Signup and view all the answers

    According to the text, what is the purpose of CSMA/CD (Carrier Sense Multiple Access with Collision Detection)?

    <p>To detect and handle collisions</p> Signup and view all the answers

    According to the text, what should a station do in the 1-persistent CSMA protocol if the medium is busy?

    <p>Continuously listen until medium becomes idle</p> Signup and view all the answers

    According to the text, what is the purpose of the jam signal in CSMA/CD?

    <p>To notify other stations of collision</p> Signup and view all the answers

    According to the text, what is the purpose of Random Access (or contention) Protocols?

    <p>To reduce the possibility of collisions</p> Signup and view all the answers

    According to the text, what is the main advantage of using CSMA/CD over other CSMA protocols?

    <p>Reduced channel idle time</p> Signup and view all the answers

    Which multiple-access method assigns a transmission channel between a sender and a receiver for a certain amount of time?

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

    What is the purpose of carrier sense in the Carrier Sense Multiple Access (CSMA) protocol?

    <p>To detect collisions on the network</p> Signup and view all the answers

    Which multiple-access method shares the bandwidth capacity in time between multiple stations?

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

    Which access method in polling uses a primary station and secondary stations for data exchanges?

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

    What is the maximum throughput in Pure ALOHA?

    <p>0.36</p> Signup and view all the answers

    Which multiple-access method carries all transmissions simultaneously on one channel?

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

    Which protocol reduces the possibility of collisions like non-persistent and reduces channel idle time like 1-persistent?

    <p>CSMA/CA</p> Signup and view all the answers

    What is the purpose of Medium Access Control (MAC) Protocols?

    <p>To control access to the transmission medium</p> Signup and view all the answers

    What is the problem with multiple nodes transmitting at the same time on a shared link?

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

    Which multiple-access method allows multiple stations to transmit at the same time, resulting in collisions and wasted bandwidth?

    <p>Random access</p> Signup and view all the answers

    Which of the following terms refers to the amount of time it takes for a signal to travel from the sender to the receiver?

    <p>Propagation delay</p> Signup and view all the answers

    Which multiple-access method divides the transmission medium into separate frequency bands?

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

    What is the main task of Multiple Access Control (MAC) protocols?

    <p>To minimize collisions</p> Signup and view all the answers

    Which protocol reduces the possibility of collisions by waiting for the medium to be idle before transmitting, and reduces channel idle time by transmitting immediately after the medium becomes idle?

    <p>p-persistent CSMA</p> Signup and view all the answers

    What is the purpose of carrier sense in the Carrier Sense Multiple Access (CSMA) protocol?

    <p>To sense the presence of other stations</p> Signup and view all the answers

    Which access method in polling can be done in order or based on a predetermined order?

    <p>Round-robin polling</p> Signup and view all the answers

    Which of the following is true about the ALOHA protocol?

    <p>ALOHA protocol requires stations to use a random retransmission time.</p> Signup and view all the answers

    Which multiple-access method carries all transmissions simultaneously on one channel?

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

    What is the maximum throughput in Pure ALOHA?

    <p>18%</p> Signup and view all the answers

    What is the purpose of carrier sense in the Carrier Sense Multiple Access (CSMA) protocol?

    <p>To listen to the medium before transmitting to avoid collisions.</p> Signup and view all the answers

    What is the maximum number of stations (n) for which stability is ensured in p-persistent CSMA?

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

    What is the purpose of Random Access (or contention) Protocols?

    <p>To allow stations to transmit at any time without coordination.</p> Signup and view all the answers

    What is the problem with multiple nodes transmitting at the same time on a shared link?

    <p>Low channel utilization</p> Signup and view all the answers

    Which of the following is true about FDMA (Frequency Division Multiple Access)?

    <p>Each station transmits continuously on the assigned frequency band</p> Signup and view all the answers

    Which of the following is true about TDMA (Time Division Multiple Access)?

    <p>The entire bandwidth capacity is shared in time between multiple stations</p> Signup and view all the answers

    Which of the following is true about CDMA (Code Division Multiple Access)?

    <p>One channel carries all transmissions simultaneously</p> Signup and view all the answers

    Which access method in polling uses a known polling order list based on some protocol?

    <p>Distributed polling</p> Signup and view all the answers

    What is the purpose of the listen state in a token-passing network?

    <p>To check the destination address of arriving bits</p> Signup and view all the answers

    Which of the following is a restriction of CSMA/CD (Carrier Sense Multiple Access with Collision Detection)?

    <p>Packet transmission time should be longer than the maximum propagation delay</p> Signup and view all the answers

    What is the purpose of controlled access or scheduling in medium access control protocols?

    <p>To provide fair access to the shared medium</p> Signup and view all the answers

    What is the purpose of the reservation interval in the reservation access method?

    <p>To make reservations in minislots</p> Signup and view all the answers

    What is the purpose of the poll frame in centralized polling?

    <p>To ask if a secondary station has data to send</p> Signup and view all the answers

    Which of the following is true about CSMA/CD (Carrier Sense Multiple Access with Collision Detection)?

    <p>CSMA/CD reduces the possibility of collisions by continuously listening to the medium until it becomes idle before transmitting.</p> Signup and view all the answers

    What is the purpose of the jam signal in CSMA/CD (Carrier Sense Multiple Access with Collision Detection)?

    <p>To ensure that the collision signal will stay until detected by the furthest station.</p> Signup and view all the answers

    What is the maximum number of stations (n) for which stability is ensured in p-persistent CSMA?

    <p>n x p &lt; 1</p> Signup and view all the answers

    What is the purpose of carrier sense in the CSMA (Carrier Sense Multiple Access) protocol?

    <p>To ensure that the medium is idle before transmitting.</p> Signup and view all the answers

    What is the main advantage of using CSMA/CD (Carrier Sense Multiple Access with Collision Detection) over other CSMA protocols?

    <p>CSMA/CD reduces the possibility of collisions like non-persistent CSMA.</p> Signup and view all the answers

    What is the purpose of controlled access or scheduling in medium access control protocols?

    <p>To allocate the medium to different stations based on a predetermined order.</p> Signup and view all the answers

    What is the main task of Multiple Access Protocols?

    <p>To allow multiple stations to share a common communication channel.</p> Signup and view all the answers

    Which CSMA protocol requires a station to wait a random amount of time (backoff) if the medium is busy?

    <p>Non-persistent CSMA</p> Signup and view all the answers

    What is the purpose of the CSMA/CD protocol?

    <p>To detect and handle collisions in the network</p> Signup and view all the answers

    What is the maximum number of stations (n) for which stability is ensured in p-persistent CSMA?

    <p>n x p &lt; 1</p> Signup and view all the answers

    What is the purpose of random retransmission time in the ALOHA scheme?

    <p>To reduce collisions in the network</p> Signup and view all the answers

    Which multiple-access method divides the transmission medium into separate frequency bands?

    <p>Frequency Division Multiple Access (FDMA)</p> Signup and view all the answers

    Which access method in polling can be done in order or based on a predetermined order?

    <p>Round Robin</p> Signup and view all the answers

    Which of the following is a disadvantage of ALOHA protocols?

    <p>High collision probability</p> Signup and view all the answers

    Which of the following is true about the ALOHA protocol?

    <p>Frames are transmitted at completely random times</p> Signup and view all the answers

    What is the maximum throughput in Pure ALOHA?

    <p>18%</p> Signup and view all the answers

    What is the purpose of carrier sense in the Carrier Sense Multiple Access (CSMA) protocol?

    <p>To listen to the medium to see if another transmission is in progress</p> Signup and view all the answers

    What is the main advantage of using CSMA/CD (Carrier Sense Multiple Access with Collision Detection) over other CSMA protocols?

    <p>It can detect and handle collisions</p> Signup and view all the answers

    What is the purpose of Random Access (or contention) Protocols?

    <p>To allow multiple stations to access a shared medium</p> Signup and view all the answers

    Which access method in polling can be done in order or based on a predetermined order?

    <p>Round-robin polling</p> Signup and view all the answers

    Which of the following is a disadvantage of ALOHA protocols?

    <p>Many collisions can occur when multiple nodes want to transmit</p> Signup and view all the answers

    According to the text, what is the maximum number of stations (n) for which stability is ensured in p-persistent CSMA?

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

    What is the purpose of the jam signal in CSMA/CD?

    <p>To notify other stations of a collision</p> Signup and view all the answers

    What is the problem with multiple nodes transmitting at the same time on a shared link?

    <p>Collisions occur</p> Signup and view all the answers

    Which of the following is true about CSMA/CD (Carrier Sense Multiple Access with Collision Detection)?

    <p>It uses random delays to reduce collisions</p> Signup and view all the answers

    Which multiple-access method allows multiple stations to transmit at the same time, resulting in collisions and wasted bandwidth?

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

    Which of the following is true about the ALOHA protocol?

    <p>It allows multiple stations to transmit at the same time</p> Signup and view all the answers

    What is the purpose of carrier sense in the CSMA (Carrier Sense Multiple Access) protocol?

    <p>To reduce collisions</p> Signup and view all the answers

    Which multiple-access method divides the transmission medium into separate time slots for each station to transmit?

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

    What is the purpose of the jam sequence in the CSMA/CD protocol?

    <p>To indicate a collision has occurred</p> Signup and view all the answers

    Which access method in polling uses a known polling order list based on some protocol?

    <p>Token Passing</p> Signup and view all the answers

    Which multiple-access method assigns a transmission channel between a sender and a receiver for a certain amount of time?

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

    What is the purpose of carrier sense in the CSMA protocol?

    <p>To synchronize the transmission between stations</p> Signup and view all the answers

    What is the purpose of the poll frame in centralized polling?

    <p>To check if a station has data to send</p> Signup and view all the answers

    What is the purpose of the MAC (Medium Access Control) sublayer?

    <p>To manage access to the medium</p> Signup and view all the answers

    Which multiple-access method carries all transmissions simultaneously on one channel?

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

    What happens if a collision occurs during transmission in the CSMA/CD protocol?

    <p>The transmission is aborted and a jam sequence is sent</p> Signup and view all the answers

    Which of the following is true about the purpose of the MAC (Medium Access Control) sublayer?

    <p>It coordinates the access of multiple sending/receiving nodes to the shared link.</p> Signup and view all the answers

    What is the main advantage of using TDMA (Time Division Multiple Access) over other multiple-access methods?

    <p>It allows multiple stations to share the bandwidth capacity in time.</p> Signup and view all the answers

    Which of the following is true about the purpose of carrier sense in the Carrier Sense Multiple Access (CSMA) protocol?

    <p>It reduces the possibility of collisions by waiting for the medium to be idle before transmitting.</p> Signup and view all the answers

    What is the maximum throughput in Pure ALOHA?

    <p>$ rac{1}{2e}$</p> Signup and view all the answers

    Which of the following is a disadvantage of ALOHA protocols?

    <p>They do not provide in-order access to a shared medium for every station.</p> Signup and view all the answers

    Which protocol reduces the possibility of collisions by waiting for the medium to be idle before transmitting, and reduces channel idle time by transmitting immediately after the medium becomes idle?

    <p>CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance)</p> Signup and view all the answers

    What is the purpose of Random Access (or contention) Protocols?

    <p>To minimize collisions and maximize bandwidth utilization</p> Signup and view all the answers

    According to the text, what is the maximum number of stations (n) for which stability is ensured in p-persistent CSMA?

    <p>n &lt; 1/p</p> Signup and view all the answers

    What is the purpose of the jam sequence in the CSMA/CD protocol?

    <p>To notify other stations of a collision</p> Signup and view all the answers

    Which of the following is a disadvantage of ALOHA protocols?

    <p>High collision probability</p> Signup and view all the answers

    What should a station do in the 1-persistent CSMA protocol if the medium is busy?

    <p>Listen continuously until the medium becomes idle</p> Signup and view all the answers

    What is the maximum throughput in Pure ALOHA?

    <p>0.1</p> Signup and view all the answers

    What is the purpose of carrier sense in the CSMA (Carrier Sense Multiple Access) protocol?

    <p>To detect collisions</p> Signup and view all the answers

    What is the main advantage of using TDMA (Time Division Multiple Access) over other multiple-access methods?

    <p>Higher throughput</p> Signup and view all the answers

    What is the purpose of the jam sequence in the CSMA/CD protocol?

    <p>To detect collisions during transmission</p> Signup and view all the answers

    According to the text, what is the purpose of Random Access (or contention) Protocols?

    <p>To ensure fair access to the transmission medium</p> Signup and view all the answers

    Which of the following is a disadvantage of ALOHA protocols?

    <p>High probability of collisions</p> Signup and view all the answers

    What is the main task of Multiple Access Control (MAC) protocols?

    <p>To ensure fair access to the transmission medium</p> Signup and view all the answers

    Which multiple-access method carries all transmissions simultaneously on one channel?

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

    What happens if a collision occurs during transmission in CSMA/CD?

    <p>The transmitting station stops transmission and waits for a random time before retransmitting</p> Signup and view all the answers

    Which multiple-access method divides the transmission medium into separate frequency bands?

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

    Which of the following is true about the CSMA/CD (Carrier Sense Multiple Access with Collision Detection) protocol?

    <p>It reduces the possibility of collisions by waiting for the medium to be idle before transmitting.</p> Signup and view all the answers

    What is the purpose of the jam signal in CSMA/CD (Carrier Sense Multiple Access with Collision Detection)?

    <p>To indicate that a collision has occurred and all stations should stop transmitting.</p> Signup and view all the answers

    What is the main advantage of using CSMA/CD (Carrier Sense Multiple Access with Collision Detection) over other CSMA protocols?

    <p>It reduces channel idle time by transmitting immediately after the medium becomes idle.</p> Signup and view all the answers

    What is the purpose of Random Access (or contention) Protocols?

    <p>To minimize collisions and efficiently utilize the bandwidth in a shared link.</p> Signup and view all the answers

    What is the maximum number of stations (n) for which stability is ensured in p-persistent CSMA?

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

    What is the purpose of the reservation interval in the reservation access method?

    <p>To reserve a transmission channel for a station to transmit during a specific time interval.</p> Signup and view all the answers

    What is the problem with multiple nodes transmitting at the same time on a shared link?

    <p>The link bandwidth is wasted during collision.</p> Signup and view all the answers

    Which of the following is true about CSMA/CD (Carrier Sense Multiple Access with Collision Detection)?

    <p>CSMA/CD requires a station to wait a random amount of time (backoff) if the medium is busy.</p> Signup and view all the answers

    What is the purpose of the jam signal in CSMA/CD?

    <p>To indicate that a collision has occurred and all stations should stop transmitting.</p> Signup and view all the answers

    Which multiple-access method divides the transmission medium into separate frequency bands?

    <p>FDMA (Frequency Division Multiple Access)</p> Signup and view all the answers

    Which multiple-access method shares the bandwidth capacity in time between multiple stations?

    <p>TDMA (Time Division Multiple Access)</p> Signup and view all the answers

    Which multiple-access method allows multiple stations to transmit at the same time, resulting in collisions and wasted bandwidth?

    <p>CSMA/CD</p> Signup and view all the answers

    What is the main advantage of using TDMA (Time Division Multiple Access) over other multiple-access methods?

    <p>TDMA assigns a fixed sending frequency to a transmission channel.</p> Signup and view all the answers

    Which method for controlled access provides in order access to a shared medium so that every station has a chance to transfer?

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

    According to the text, what is the purpose of CSMA/CD (Carrier Sense Multiple Access with Collision Detection)?

    <p>To provide in order access to a shared medium.</p> Signup and view all the answers

    Which of the following is a disadvantage of ALOHA protocols?

    <p>ALOHA protocols have a high probability of collisions.</p> Signup and view all the answers

    True or false: The MAC Layer is responsible for error and flow control.

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

    True or false: The main task of Multiple Access Protocols is to maximize collisions.

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

    True or false: Random Access Protocols assign control over one station to another.

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

    True or false: Throughput is the amount of time it takes for the signal to travel from the sender to the receiver.

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

    True or false: Random Access Protocols do not assign control to any station.

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

    True or false: CSMA/CD reduces collisions and idle time on the channel.

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

    True or false: The MAC sublayer is responsible for determining when a station can use the link.

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

    True or false: The ALOHA protocol was developed at the University of Hawaii in the early 1970s to connect computers situated on different Hawaiian islands.

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

    True or false: In Pure ALOHA, frames are transmitted at completely random times.

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

    True or false: Slotted ALOHA divides time into slots equal to a frame transmission time.

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

    True or false: The maximum throughput in Pure ALOHA occurs at G = 1/2 which is 18%.

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

    True or false: Carrier Sense Multiple Access (CSMA) protocol requires a station to wait for the medium to be clear before transmitting.

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

    True or false: The maximum number of stations (n) for which stability is ensured in p-persistent CSMA is determined by the formula: n ≤ (1/G) - 1.

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

    True or false: The purpose of carrier sense in the CSMA protocol is to reduce the possibility of collision.

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

    True or false: Collision can only happen when more than one station begin transmitting within a short time period?

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

    True or false: The longer the propagation delay, the better the performance of the protocol?

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

    True or false: Non-persistent CSMA is a protocol where a station transmits immediately if the medium is idle and waits a random amount of time if the medium is busy?

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

    True or false: 1-persistent CSMA reduces the probability of collisions compared to non-persistent CSMA?

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

    True or false: P-persistent CSMA reduces the possibility of collisions like non-persistent and reduces channel idle time like 1-persistent?

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

    True or false: CSMA/CD (Carrier Sense Multiple Access with Collision Detection) is widely used for bus topology LANs?

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

    True or false: If a collision has occurred, the channel is unstable until colliding packets have been fully transmitted in CSMA/CD?

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

    True or false: FDMA assigns a frequency to a transmission channel permanently.

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

    True or false: TDMA assigns a fixed sending frequency to a transmission channel between a sender and a receiver for a certain amount of time.

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

    True or false: CDMA carries all transmissions simultaneously on one channel.

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

    True or false: Reservation access method organizes transmissions into variable length cycles.

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

    True or false: Polling can be done in order (Round-Robin) or based on a predetermined order.

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

    True or false: Token-Passing network has two states for station interface: listen state and transmit state.

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

    True or false: Channelization is a multiple-access method that shares the available bandwidth of a link in time, frequency, or through code.

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

    True or false: FDMA and TDMA are examples of frequency-division multiple access methods.

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

    True or false: CDMA uses specific codes to recover data for desired stations.

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

    Study Notes

    Multiple Access Control (MAC) Layer

    • The data link layer is divided into two sublayers: Link Layer Control (LLC) and Medium Access Control (MAC)
    • The MAC sublayer is responsible for error and flow control, framing, and MAC addressing
    • Multiple Access Control (MAC) protocols coordinate the access of multiple sending/receiving nodes to a shared link

    Problem of Multiple Access

    • When two or more nodes transmit at the same time, their frames will collide, wasting link bandwidth
    • Solution: MAC protocols minimize collisions to utilize bandwidth by determining when a station can use the link, what a station should do when the link is busy, and what a station should do when involved in a collision

    Throughput and Propagation Delay

    • Throughput: the amount of data moved successfully from one place to another in a given time period
    • Propagation delay: the time it takes for the head of a signal to travel from the sender to the receiver

    Random Access Protocols

    • ALOHA: a random access scheme developed at the University of Hawaii in the early 1970s
    • Pure ALOHA:
      • Frames are transmitted at completely random times
      • A station can transmit at any time
      • If no acknowledgment is received, the sender assumes the frame was destroyed and resends it after a random amount of time
      • Maximum throughput is 18% at G = 1/2
    • Slotted ALOHA:
      • Time is divided into slots equal to the frame transmission time
      • A station can transmit only at the beginning of a slot
      • Maximum throughput is 37% at G = 1

    Carrier Sense Multiple Access (CSMA)

    • A user wishing to transmit first listens to the medium to see if another transmission is in progress
    • If the medium is idle, the station transmits; otherwise, it waits
    • Vulnerable time for CSMA is the maximum propagation time

    Types of CSMA Protocols

    • Non-Persistent CSMA:
      • A station with frames to be sent senses the medium
      • If the medium is idle, the station transmits; otherwise, it waits for a random amount of time and repeats
    • 1-Persistent CSMA:
      • A station with frames to be sent senses the medium
      • If the medium is idle, the station transmits immediately; otherwise, it continuously listens until the medium is idle
    • P-Persistent CSMA:
      • A station with frames to be sent senses the medium
      • If the medium is idle, the station transmits with probability p; otherwise, it waits one time unit and repeats

    CSMA/CD (Carrier Sense Multiple Access with Collision Detection)

    • If a collision occurs, the sender stops transmission and transmits a jam signal to notify other stations
    • After sending the jam signal, the station waits for a random amount of time and then retransmits the frame
    • CSMA/CD is widely used in bus topology LANs (IEEE 802.3, Ethernet)

    Controlled Access or Scheduling

    • Provides in-order access to the shared medium so that every station has a chance to transfer (fair protocol)
    • Eliminates collisions completely
    • Three methods for controlled access: Reservation, Polling, and Token Passing

    Reservation Access Method

    • Stations take turns transmitting a single frame at a full rate
    • Transmissions are organized into variable-length cycles
    • Each cycle begins with a reservation interval that consists of N minislots
    • Stations make reservations in their own minislot and then transmit their data frames

    Polling

    • Stations take turns accessing the medium
    • Two models: Centralized and Distributed Polling
    • Centralized Polling:
      • One device is assigned as the primary station and the others as secondary stations
      • All data exchanges are done through the primary
      • When the primary has a frame to send, it sends a select frame that includes the address of the intended secondary
    • Distributed Polling:
      • No primary and secondary stations
      • Stations have a known polling order list made based on some protocol
      • The station with the highest priority will have the access right first, then it passes the access right to the next station

    Token-Passing Network

    • Stations interface is in two states: Listen and Transmit
    • Station captures a special frame called a free token and transmits its frames
    • Sending station is responsible for reinserting the free token into the ring medium and removing the transmitted frame from the medium

    Channelization

    • FDMA (Frequency Division Multiple Access): assigns a frequency to a transmission channel permanently
    • TDMA (Time Division Multiple Access): assigns a fixed sending frequency to a transmission channel between a sender and a receiver for a certain amount of time
    • CDMA (Code Division Multiple Access): one channel carries all transmissions simultaneously, each station codes its data signal with a specific code before transmission, and receivers use these codes to recover the data for the desired station

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    Related Documents

    CMP5123 Week 4 MAC Layer Protocols PDF

    Description

    Test your knowledge on different CSMA protocols and their vulnerability to collisions. Learn about the impact of propagation time and how it affects the performance of these protocols.

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