Write A 4 To 5 Page Report Excluding Cover Page And R 644437

Write A 4 To 5 Page Report Excluding Cover Page And References

Write a 4 to 5-page report (excluding cover page and references) answering the following questions. 1. What are the functions of data link? 2. Why and where is flow control needed? Explain its parameters. 3. Explain stop-and-wait flow control with special reference to the handling of (i) a damaged frame (ii) a lost frame. 4. Explain HDLC. What are the categories of HDLC stations? 5. What is the configuration and modes of HDLC? 6. What does "switching" mean? Explain the three possible switching methods.

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The data link layer is a fundamental component of network architecture, responsible for providing reliable transmission of data across a physical link. Its primary functions include framing, addressing, error detection and correction, flow control, and media access control. Framing involves encapsulating raw bits into frames for easier handling and synchronization. Addressing ensures that data reaches the correct destination on a local network, usually through MAC addresses. Error detection techniques, such as CRC, help identify corrupted frames, while error correction mechanisms may also be employed to recover from errors. Additionally, the data link layer manages access to shared media, preventing collisions and ensuring orderly data transmission.

Flow control is crucial in network communications to prevent the sender from overwhelming the receiver with too much data too quickly. This is particularly important in situations where there is a speed mismatch between devices or when the receiver's buffer is limited. Flow control mechanisms regulate the rate of data transmission to ensure that the receiver can process incoming data without overflow. Parameters associated with flow control include window size (in sliding window protocols), buffer size, and timing intervals for acknowledgment messages. Proper flow control enhances network efficiency, prevents data loss, and maintains data integrity.

Stop-and-wait flow control is a simple protocol where the sender transmits a frame and waits for an acknowledgment before sending the next frame. When a damaged frame occurs, the receiver detects errors using error detection codes and discards the corrupted frame. The sender, upon timeout or receipt of a negative acknowledgment (NAK), retransmits the damaged frame. In the case of a lost frame, the sender does not receive an acknowledgment within the expected time and retransmits the frame after a timeout. This process ensures reliable data transmission but can be inefficient over long-distance or high-latency links due to its waiting periods.

High-Level Data Link Control (HDLC) is a widely used protocol for framing and managing data transmission over point-to-point and multipoint links. HDLC provides both connection-oriented and connectionless services and employs bit-oriented framing. HDLC frames include fields such as flag delimiters, address, control, information, and checksum. The protocol specifies mechanisms for error detection, retransmission, and flow control, making it suitable for a variety of network environments.

HDLC stations are categorized into two types: Primary stations and Secondary stations. The primary station is responsible for controlling the link, initiating and ending sessions, and managing other stations. The secondary stations follow the primary's commands and respond to their requests, often used in multipoint configurations. These categories ensure structured and managed communication across multiple devices.

The configuration of HDLC includes different modes such as Normal Response Mode (NRM), Asynchronous Balanced Mode (ABM), and Asynchronous Response Mode (ARM). NRM is used mainly in master-slave configurations where the primary manages the link. ABM allows both stations to operate as equals, capable of initiating transmissions, which makes it suitable for peer-to-peer networks. ARM is primarily used for asymmetric communication, where secondary stations respond to the primary's polls. These modes provide flexibility to accommodate different network requirements.

Switching in networking refers to the method by which data packets are directed from source to destination across a network. It involves selecting the path for data transfer and forwarding data accordingly. The three common switching methods are circuit switching, packet switching, and message switching. Circuit switching establishes a dedicated communication path before data transfer begins, ensuring a continuous and reliable connection. Packet switching divides data into packets that are routed independently through the network, optimizing resource utilization. Message switching involves storing and forwarding entire messages at intermediate nodes, useful in early networking systems but less common today. Each method has advantages and disadvantages depending on the use case, such as voice communication, data transfer, or multimedia streaming.

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