Question

Suppose hosts A and B are connected by a link. Host A continuously transmits the current time from a high-precision clock, at a regular rate, fast enough to consume all the available bandwidth. Host \(\mathrm{B}\) reads these time values and writes them each paired with its own time from a local clock synchronized with A's. Give qualitative examples of B's output assuming the link has (a) high bandwidth, high latency, low jitter (b) low bandwidth, high latency, high jitter (c) high bandwidth, low latency, low jitter, occasional lost data For example, a link with zero jitter, a bandwidth high enough to write on every other clock tick, and a latency of 1 tick might yield something like \((0000,0001)\), \((0002,0003),(0004,0005)\).

Short answer

a) (0000, 0100), (0001, 0101), (0002, 0102) b) (0000, 0100), (0002, 0125), (0006, 0200) c) (0000, 0001), (0001, 0002), (0003, 0004)

Step-by-step solution

- Understand the Concept

A continuously transmits time values that B pairs with its own local time. The examples will vary depending on the characteristics of the link: high bandwidth, high latency, low jitter; low bandwidth, high latency, high jitter; and high bandwidth, low latency, low jitter, occasional lost data.

- Case (a): High Bandwidth, High Latency, Low Jitter

High bandwidth means frequent time ticks, high latency means a constant delay, and low jitter means minimal variation. Thus, B will receive time values from A with a consistent delay. Example output: (0000, 0100), (0001, 0101), (0002, 0102), ...

- Case (b): Low Bandwidth, High Latency, High Jitter

Low bandwidth results in less frequent time ticks being received, high latency introduces consistent delays, and high jitter results in variable delays. Example output: (0000, 0100), (0002, 0125), (0006, 0200), ...

- Case (c): High Bandwidth, Low Latency, Low Jitter, Occasional Lost Data

High bandwidth means frequent time ticks, low latency means minimal delay, low jitter means consistent delay; however, occasional data loss results in missing time pairs. Example output: (0000, 0001), (0001, 0002), (0003, 0004), (0004, 0005), ...

Key concepts

Bandwidth

Bandwidth is a measure of how much data can be transferred from one point to another within a network in a given amount of time.
It is usually measured in bits per second (bps).
High bandwidth means a large amount of data can be transmitted quickly, whereas low bandwidth means less data can be transmitted and typically at a slower rate.
In our exercise, comparing high bandwidth to low bandwidth:

• High bandwidth allows Host A to transmit time values very frequently. This means Host B receives a lot of data in a short time.
• Low bandwidth means Host A can only send time values less frequently. Host B receives data less often, creating bigger gaps between time values.

Understanding bandwidth helps in gauging the capacity of your network and planning for data transmission needs.

Latency

Latency is the time delay between a data packet being sent and received over the network.
It is usually measured in milliseconds (ms).
High latency means there is a longer delay, while low latency implies a much shorter delay. In our exercise:

• High latency results in a significant delay between Host A sending and Host B receiving the data..
• Low latency means the time values sent by Host A are received almost immediately by Host B, making the communication nearly real-time.

Latency is critical for applications requiring timely data delivery, such as online gaming or video conferencing.

Jitter

Jitter refers to the variation in packet arrival times.
It is the inconsistency or variability in the delay of data packets.
High jitter means packet arrival times fluctuate significantly, while low jitter implies consistent delivery times.
In our exercise, jitter affects how smoothly data is received:

• With low jitter, the time values from Host A arrive at Host B consistently, creating a stable communication link.
• High jitter results in uneven arrival times of time values at Host B, causing irregularities and potential disarray in data processing.

Jitter can severely impact real-time applications like VoIP (voice over IP) and live video streaming.

Data Loss

Data loss occurs when data packets fail to reach their destination.
It can result from network congestion, faulty hardware, or interference.
In our exercise:

• High bandwidth, low latency, and low jitter usually lead to minimal data loss. However, occasional lost data may still occur, causing missing time pairs in the output.

Data loss can be critical in applications requiring high data integrity. Managing data loss involves implementing error detection and correction mechanisms to ensure consistent communication.