Question

Discuss the relative performance needs of the following applications, in terms of average bandwidth, peak bandwidth, latency, jitter, and loss tolerance: (a) File server (b) Print server (c) Digital library (d) Routine monitoring of remote weather instruments (e) Voice (f) Video monitoring of a waiting room (g) Television broadcasting

Short answer

Applications vary greatly, with file servers and digital libraries needing high average bandwidth; routine monitoring and print servers needing low; voice and video monitoring require low latency and minimal jitter; television broadcasting needs the most stringent conditions overall.

Step-by-step solution

- File Server

A file server needs a high average bandwidth to handle multiple simultaneous file transfers. Peak bandwidth requirements can be moderate to handle occasional large transfers. Latency must be low for rapid file access. Jitter is not a major concern, and loss tolerance is low since file transfers need to be accurate.

- Print Server

A print server requires moderate average bandwidth as print jobs are generally not large. Peak bandwidth can be low to moderate depending on print job size. Latency should be low to ensure timely print completions. Jitter and loss tolerance are similar to a file server.

- Digital Library

A digital library needs a high average bandwidth for data retrieval operations. The peak bandwidth requirement is high to accommodate multiple users accessing large files concurrently. Latency should be low for quick access. Jitter is not critical. Loss tolerance must be low to maintain data integrity.

- Routine Monitoring of Remote Weather Instruments

Routine monitoring of remote weather instruments needs a low average bandwidth due to the small size of the data. Peak bandwidth is also low. Latency should be relatively low for real-time updates. Jitter and loss tolerance should be minimal to ensure accurate reporting.

- Voice

Voice communication requires moderate average and peak bandwidth. Latency must be very low to avoid delays in conversation. Jitter must be minimal to maintain sound quality, and loss tolerance is moderate as minor packet loss can be compensated with error correction.

- Video Monitoring of a Waiting Room

Video monitoring requires high average bandwidth to stream live footage. Peak bandwidth can be high depending on video quality. Latency should be low for real-time monitoring. Jitter must be minimal to avoid video quality degradation, and loss tolerance is low to maintain video integrity.

- Television Broadcasting

Television broadcasting needs very high average and peak bandwidth for high-definition video and audio transmission. Latency must be low for live broadcasts. Jitter should be minimal to avoid disruption, and loss tolerance is low to ensure continuous, high-quality transmission.

Key concepts

Average Bandwidth

Average bandwidth refers to the average rate at which data is transferred across a network. It is measured in bits per second (bps) and directly impacts the overall efficiency of an application. For instance, a file server or a digital library requires high average bandwidth to handle multiple data transfer requests simultaneously. Meanwhile, applications like routine monitoring of remote weather instruments need low average bandwidth due to the smaller volume of data being transmitted.

To understand it better:

• High average bandwidth: Necessary for applications with constant data transfer needs like video monitoring and television broadcasting.
• Low average bandwidth: Sufficient for applications with intermittent data transfers, such as print servers or routine monitoring of weather instruments.

Peak Bandwidth

Peak bandwidth is the highest data transfer rate an application requires at any given moment. This measure is crucial for managing short bursts of high data flow. For example, an application like a digital library needs a high peak bandwidth to support multiple users accessing large files at the same time.

The requirements can vary:

• High peak bandwidth: Required when there are sudden spikes in data transfer, such as during file transfers on a file server, or video streams on television broadcasting.
• Moderate peak bandwidth: Suited for applications like print servers, which occasionally handle larger print jobs.
• Low peak bandwidth: For applications with minimal data transfer peaks, such as routine weather monitoring.

Latency

Latency measures the delay between the transmission and reception of data packets. Low latency is critical for applications where timing is paramount, such as voice communication and real-time video monitoring.

Here’s how it affects different applications:

• Very low latency: Needed for voice and live video applications to ensure there are no noticeable delays.
• Low latency: Important for applications like file servers and digital libraries, where users expect quick responses.
• Moderate latency: Acceptable for less time-sensitive applications such as print servers and weather monitoring.

Jitter

Jitter is the variation in packet arrival times, which can lead to performance issues, especially in real-time applications. Minimizing jitter is essential for maintaining quality in voice and video streaming. If the network experiences high jitter, users might notice glitches or disruptions in the service.

Consider these points:

• Minimal jitter: Crucial for voice and video applications to maintain sound and picture quality.
• Moderate jitter: Tolerable for applications like digital libraries or file servers, where slight variations don't impact functionality as much.
• Negligible jitter: Because jitter doesn't significantly affect print servers or routine weather monitoring.

Loss Tolerance

Loss tolerance refers to how well an application can handle data packet losses. Some applications, like file servers and digital libraries, have very low loss tolerance because accuracy in data is crucial. On the other hand, voice communication can tolerate some packet loss due to error correction mechanisms.

Here’s a closer look:

• Low loss tolerance: Required for applications where data accuracy and integrity are critical, such as file servers, digital libraries, and television broadcasting.
• Moderate loss tolerance: Suitable for less critical applications like voice communication, where slight packet loss can be compensated with signal processing techniques.
• High loss tolerance: Rare, but could apply to non-critical monitoring applications.