75 Questions
What is the main task of Multiple Access Protocols?
Minimize collisions to utilize bandwidth
Which layer is responsible for error and flow control in the data link layer?
Link Layer Control (LLC)
What is the purpose of Medium Access Control (MAC) protocols?
Coordinate the access of multiple nodes to a shared link
What is the role of the MAC Control sublayer in the data link layer?
Manages medium access coordination
What does the term 'throughput' refer to in networking?
Amount of data moved successfully in a given time period
How is the propagation delay defined in networking?
Amount of time for signal to travel from sender to receiver
What problem arises when two or more nodes transmit at the same time in a broadcast link?
Frames collide and link bandwidth is wasted
What is the characteristic of FDMA (Frequency Division Multiple Access)?
Transmission medium is divided into separate frequency bands
What is the characteristic of TDMA (Time Division Multiple Access)?
The entire bandwidth capacity is a single channel with its capacity shared in time between M stations
What is the characteristic of CDMA (Code Division Multiple Access)?
One channel carries all transmissions simultaneously
What does TDMA (Time Division Multiple Access) use to share the bandwidth capacity?
Time slots
How does FDMA assign the transmission frequency?
Fixed sending frequency to a transmission channel between a sender and a receiver for a certain amount of time
What is the limitation of a node in FDMA?
A node is limited to an average rate even when it is the only node with frame to be sent
What is the main feature of CDMA data transmission?
Each station codes its data signal by specific codes before transmission
What distinguishes TDMA from FDMA and CDMA in terms of bandwidth sharing?
The entire bandwidth capacity is a single channel with its capacity shared in time between M stations
What is the method used by CDMA stations to recover the data for the desired station?
The stations receivers use specific codes to recover the data for the desired station
What is the main function of Multiple Access Control (MAC) protocols?
Minimizing collisions to utilize bandwidth
What is the purpose of the Medium Access Control (MAC) layer in the data link layer?
Coordinating the transmission of active nodes and minimizing collisions
What does the term 'throughput' refer to in networking?
The amount of data moved successfully in a given time period
How is the propagation delay defined in networking?
The amount of time it takes for the signal to travel from sender to receiver
What is the characteristic of TDMA (Time Division Multiple Access)?
Divides time into slots for individual node transmission
What is the role of the Link Layer Control (LLC) in the data link layer?
Responsible for error and flow control
What is the limitation of a node in FDMA (Frequency Division Multiple Access)?
Restricted to a specific frequency band for transmission
Which protocol divides time into slots equal to frame transmission time?
Slotted ALOHA
What is the vulnerable time for CSMA?
Maximum propagation delay
What is the main characteristic of 1-Persistent CSMA protocol?
Avoiding idle channel time
What is the purpose of Non-Persistent CSMA protocol?
To sense the medium and wait a random amount of time if it's busy
What does ALOHA network do whenever there's a packet to transmit?
Transmits on the same radio channel
What is the role of CSMA protocol before transmitting?
Listen to the medium
What is the maximum propagation delay in networking?
The time taken for a bit of a frame to travel between the two most widely separated stations
What is the characteristic of FDMA (Frequency Division Multiple Access)?
Transmission medium is divided into M separate frequency bands
What distinguishes TDMA from FDMA and CDMA in terms of bandwidth sharing?
Entire bandwidth capacity is a single channel with its capacity shared in time between M stations
What is the characteristic of CDMA (Code Division Multiple Access)?
One channel carries all transmissions simultaneously
What is the limitation of a node in FDMA?
Node is limited to an average rate even when it is the only node with frame to be sent
How does TDMA (Time Division Multiple Access) share the bandwidth capacity?
Entire bandwidth capacity is a single channel with its capacity shared in time between M stations
What is the method used by CDMA stations to recover the data for the desired station?
Each station codes its data signal by specific codes before transmission
What is the characteristic of TDMA (Time Division Multiple Access)?
The entire bandwidth capacity is a single channel with its capacity shared in time between M stations
What is the characteristic of CDMA (Code Division Multiple Access)?
One channel carries all transmissions simultaneously
What does FDMA (Frequency Division Multiple Access) use to assign the fixed sending frequency to a transmission channel?
Transmission medium is divided into M separate frequency bands
What is the characteristic of TDMA (Time Division Multiple Access)?
The entire bandwidth capacity is a single channel with its capacity shared in time between M stations
In CSMA/CD, what happens if a collision is detected during transmission?
The sender aborts transmission, transmits a jam signal, and waits for a random amount of time before retransmitting
What is the main advantage of Controlled Access or Scheduling protocols over CSMA/CD?
They provide fair access to the shared medium and eliminate collisions completely
What method does the Reservation Access Method use to organize transmissions?
Stations take turns transmitting frames at a full rate and make reservations in minislots
What is the primary role of the Polling method in Controlled Access protocols?
Centralized or distributed coordination of data exchanges
What is the key characteristic of Token-Passing network method?
Stations listen to arriving bits in the listen state and transmit frames after capturing a free token
What is the primary purpose of Channelization in multiple-access methods?
To share the available bandwidth of a link in time, frequency, or through code between different stations
How does TDMA (Time Division Multiple Access) share the channel's bandwidth?
It shares the channel in time slots
Which protocol requires stations to use a random retransmission time to avoid collisions?
Pure ALOHA
What does Carrier Sense Multiple Access (CSMA) protocol require stations to do before transmitting?
Listen to the medium
What is the maximum propagation delay?
Time for a bit of a frame to travel between the two most widely separated stations
What does Non-Persistent CSMA protocol involve when the medium is busy?
Sensing the medium and waiting a random amount of time
What is the vulnerable time for CSMA?
Maximum propagation time
What does 1-Persistent CSMA protocol aim to avoid?
Idle channel time
What do different types of CSMA protocols determine?
Station behavior when the medium is idle and busy
What is the primary purpose of CSMA/CD (Carrier Sense Multiple Access with Collision Detection) over CSMA?
To detect collisions during transmission and reduce channel wastage
What is the maximum propagation delay for detecting a collision in CSMA/CD?
Twice the maximum propagation delay of the medium
What method does the Reservation Access Method use to organize transmissions?
Stations take turns transmitting frames at a full rate and make reservations in minislots
What is the characteristic of FDMA (Frequency Division Multiple Access)?
Assigns a frequency to a transmission channel
What does TDMA (Time Division Multiple Access) use to share the channel's bandwidth?
Time slots
What is the main function of Multiple Access Control (MAC) protocols?
To coordinate access to the shared medium
What is the main advantage of Controlled Access or Scheduling protocols over CSMA/CD?
They eliminate collisions completely
What is the vulnerable time for pure ALOHA protocol?
$2T_{fr}$
What is the maximum throughput for slotted ALOHA?
$G = 1$ which is 37%
What is the main advantage of ALOHA protocols?
A node can transmit continuously at the full rate of the channel if it is the only node with frames
What is the vulnerable time for CSMA protocol?
The maximum propagation time
What does 1-persistent CSMA protocol do to avoid idle channel time?
Listens to the medium and transmits if idle
What determines the maximum throughput for pure ALOHA?
G = 1/2 which is 18%
What is the main disadvantage of ALOHA protocols?
If multiple nodes want to transmit, many collisions can occur
What is the main advantage of P-persistent CSMA over non-persistent CSMA?
Reduces the possibility of collisions
In CSMA/CD, what does a station do if a collision is detected during transmission?
Abort transmission, transmit a jam signal, backoff, and retransmit
What is the restriction for CSMA/CD regarding packet transmission time and collision detection?
Packet transmission time should be at least as long as the time needed to detect a collision
What is the purpose of the Poll frame in the centralized polling access method?
To ask if secondary stations have data to send
What is the role of a station in a Token-Passing network when in the transmit state?
Capture a free token and transmit frames
What does FDMA (Frequency Division Multiple Access) assign to a transmission channel?
A frequency
What is the primary advantage of TDMA (Time Division Multiple Access) over FDMA?
More efficient use of available bandwidth
Study Notes
CSMA/CD and Controlled Access Protocols
- CSMA/CD (Carrier Sense Multiple Access with Collision Detection) overcomes the inefficiency of CSMA by detecting collisions during transmission and reducing channel wastage.
- CSMA/CD is widely used for bus topology LANs, such as IEEE 802.3 Ethernet.
- If a collision is detected during transmission in CSMA/CD, the sender aborts transmission, transmits a jam signal to notify other stations, and then waits for a random amount of time before retransmitting the frame.
- The time it takes to detect a collision in CSMA/CD is at most twice the maximum propagation delay of the medium.
- The packet transmission time in CSMA/CD should be at least as long as the time needed to detect a collision to have an advantage over CSMA.
- Controlled Access or Scheduling protocols provide fair access to the shared medium and eliminate collisions completely.
- There are three methods for controlled access: Reservation, Polling, and Token Passing.
- In the Reservation Access Method, stations take turns transmitting frames at a full rate and make reservations in minislots to organize transmissions.
- Polling can be centralized or distributed, with the primary station coordinating data exchanges and asking secondary stations for data.
- Token-Passing network involves stations listening to arriving bits in the listen state and transmitting frames after capturing a free token in the transmit state.
- Channelization is a multiple-access method for sharing the available bandwidth of a link in time, frequency, or through code, between different stations.
- FDMA (Frequency Division Multiple Access) assigns a frequency to a transmission channel, while TDMA (Time Division Multiple Access) shares the channel in time slots.
CSMA/CD and Controlled Access Protocols
- CSMA/CD (Carrier Sense Multiple Access with Collision Detection) overcomes the inefficiency of CSMA by detecting collisions during transmission and reducing channel wastage.
- CSMA/CD is widely used for bus topology LANs, such as IEEE 802.3 Ethernet.
- If a collision is detected during transmission in CSMA/CD, the sender aborts transmission, transmits a jam signal to notify other stations, and then waits for a random amount of time before retransmitting the frame.
- The time it takes to detect a collision in CSMA/CD is at most twice the maximum propagation delay of the medium.
- The packet transmission time in CSMA/CD should be at least as long as the time needed to detect a collision to have an advantage over CSMA.
- Controlled Access or Scheduling protocols provide fair access to the shared medium and eliminate collisions completely.
- There are three methods for controlled access: Reservation, Polling, and Token Passing.
- In the Reservation Access Method, stations take turns transmitting frames at a full rate and make reservations in minislots to organize transmissions.
- Polling can be centralized or distributed, with the primary station coordinating data exchanges and asking secondary stations for data.
- Token-Passing network involves stations listening to arriving bits in the listen state and transmitting frames after capturing a free token in the transmit state.
- Channelization is a multiple-access method for sharing the available bandwidth of a link in time, frequency, or through code, between different stations.
- FDMA (Frequency Division Multiple Access) assigns a frequency to a transmission channel, while TDMA (Time Division Multiple Access) shares the channel in time slots.
Test your knowledge of CSMA/CD and Controlled Access Protocols with this quiz. Explore the concepts of collision detection, jam signals, and fair access methods such as Reservation, Polling, and Token Passing. Gain insights into multiple-access methods like FDMA and TDMA for efficient bandwidth sharing.
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