Computer Networks And Internet Protocol - Week 7 Assignment 7 | NPTEL | JAN 2023

Computer Networks And Internet Protocol - Week 7 | Assignment : Answer with Explanation

Which of the following are reasons for affecting network performance due to congest

a. Bandwidth
b. Delay
c. Jitter
d. All of the above

Answer

d. All of the above

Based on QoS requirements, video conferencing comes under which class of application?

a. constant bit rate
b. Real-Time variable bit rate
c. Non-real-time variable bitrate
d. Available bit rate or best-effort

Answer

b. Real-Time variable bit rate

- Constant bit rate (e.g. telephone applications – VoIP)
- Real time variable bit rate (e.g. videoconferencing)
- Non real-time variable bit rate (e.g. on demand video streaming – IPTV)
- Available bit rate or Best effort (e.g. File transfer)

What is the transmission delay for pushing a packet of size 1MB through a network with bandwidth 16Mbps?

a. 2 seconds
b. 0.5 seconds
c. 1 second
d. 10 second

Answer

b. 0.5 seconds
Amount of time to push all the packet bits in the network

The transmission delay for pushing a packet of size 1MB through a network with bandwidth 16Mbps can be calculated using the following formula:

Transmission delay = packet size / bandwidth

where packet size is in bits and bandwidth is in bits per second.

To convert 1MB to bits, we need to multiply it by 8 (since there are 8 bits in a byte). Therefore, the packet size in bits is:
1MB = 1,000,000 bytes
1,000,000 bytes * 8 bits/byte = 8,000,000 bits
Now, we can plug in the values to the formula:
Transmission delay = 8,000,000 bits / 16Mbps
Simplifying:

Transmission delay = 8,000,000 bits / (16 * 10^6 bits/s)
Transmission delay = 0.5 seconds
Therefore, the transmission delay for pushing a packet of size 1MB through a network with bandwidth 16Mbps is 0.5 seconds.

The primary goal of QoS is

a. Degrade loss characteristics
b. Control jitter
c. Increase communication latency
d. None of the above

Answer

b. Control jitter

Quality of Service (QoS) refers to the capability of a network to provide better service to selected network traffic over various technologies, including Frame Relay, Asynchronous Transfer Mode (ATM), Ethernet and 802.1 networks, SONET, and IP-routed networks that may use any or all of these underlying technologies. The primary goal of QoS is to provide priority including dedicated bandwidth, controlled jitter and latency (required by some real-time and interactive traffic), and improved loss characteristics.

If it is seen in some intermediate step that it wont be possible to service the QoS requirements for some specific classes of packets then those packets are droppped.

a. True
b. False

Answer

a. True

Yes, that is correct. In Quality of Service (QoS) implementations, packets are classified into different classes based on their priority and importance. Each class of packets is assigned specific QoS requirements, such as bandwidth, latency, and jitter.

If, during the processing of a packet, it is determined that it will not be possible to meet the QoS requirements for a particular class of packets, then dropping the packet may be necessary. This is because allowing the packet to continue through the network could cause other packets to experience delays or other issues, which could further impact the overall network performance and QoS.

Packet dropping is a technique used to manage network congestion and maintain QoS levels by selectively discarding packets that do not meet the QoS requirements. The decision to drop a packet is typically based on various factors, including the packet's priority, the state of the network, and the network's available resources.

Which of the following is not a benefit of traffic shaping?

a. Reducing network congestion
b. Controlling the rate of traffic flow
c. Improving network efficiency
d. Prioritizing certain types of traffic

Answer

d. Prioritizing certain types of traffic

Traffic Shaping: Control the outgoing traffic rate irrespective of the incoming traffic rate (e.g. constant bit rate output from the interface buffer)

Which of the follwing is NOT a benefit of Traffic Scheduling ?

a. Ensuring Timely delivery of time sensitive traffic
b. Prioritizing high bandwidth traffic over low bandwidth traffic
c. Imrpoving network efficiency
d. Reducing network congestion.

Answer

b. Prioritizing high bandwidth traffic over low bandwidth traffic

Which of the following is an example of a traffic scheduling algorithm ?

a. Weighted Fair Queuing (WFQ)
b. Leaky Bucket
c. Token Bucket
d. Random Early Detection (RED)

Answer

a. Weighted Fair Queuing (WFQ)
Weighted Fair Queuing (WFQ) is a traffic scheduling algorithm that works by assigning weights to different flows of data and ensuring that each flow gets a fair share of the available bandwidth. This helps to prevent any one flow from monopolizing the network and causing congestion.
Leaky Bucket and Token Bucket are examples of traffic shaping algorithms, which are used to regulate the flow of data on a network. They work by controlling the rate at which packets are sent, to ensure that the network is not overwhelmed with traffic.
Random Early Detection (RED) is a congestion avoidance algorithm that works by dropping packets before the network becomes congested. It does this by randomly dropping packets when the network is not yet congested, to signal to sending hosts that they need to slow down their data transmission.

Which of the follwing is NOT a benefit of the Leaky Bucket algorithm ?

a. Controlling the rate of traffic flow
b. Preventing network congetion
c. Reducing the impact of bursty traffic.
d. Prioritizing high-bandwidth traffic over low-bandwidth traffic

Answer

Option d. "Prioritizing high-bandwidth traffic over low-bandwidth traffic" is NOT a benefit of the Leaky Bucket algorithm.

a. Controlling the rate of traffic flow: One of the primary benefits of the Leaky Bucket algorithm is that it can control the rate of traffic flow through a network. The algorithm works by regulating the amount of data that can be transmitted over a certain period of time, ensuring that the network is not overwhelmed by too much traffic at once.

b. Preventing network congestion: Another benefit of the Leaky Bucket algorithm is that it can help prevent network congestion. By controlling the rate of traffic flow, the algorithm ensures that the network is not inundated with too much data, which can cause delays and other performance issues.

c. Reducing the impact of bursty traffic: The Leaky Bucket algorithm is also useful for reducing the impact of bursty traffic. Bursty traffic refers to sudden, intermittent surges in network traffic, which can cause problems for networks that are not equipped to handle them. The Leaky Bucket algorithm can help smooth out these surges by regulating the flow of data.

d. Prioritizing high-bandwidth traffic over low-bandwidth traffic: The Leaky Bucket algorithm does not prioritize high-bandwidth traffic over low-bandwidth traffic. Instead, it treats all traffic equally, regulating the flow of data according to a set of predetermined rules. Other algorithms, such as Weighted Fair Queuing (WFQ), are better suited for prioritizing traffic based on bandwidth requirements.

In a network with a maximum queue size of 100 packets and a minimum threshold of 40 packets, what is the drop probability when the current queue size is 70 packets and the maximum threshold is set to 90 packets using the RED algorithm?

a. 20%
b. 40%
c. 60%
d. 80%

Answer

a. 20%

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Computer Networks And Internet Protocol, Week 7: Assignment 7,noc23_cs48