JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD MCA 2020 INTERNET OF THINGS Previous Question Paper (October/ November - 2020 - R15)

IoT protocols facilitate communication between devices, gateways, and cloud platforms. They are categorized based on their function in the communication stack:

1. Link Layer Protocols: These determine how data is physically transmitted over the network. Examples include 802.3 (Ethernet), 802.11 (Wi-Fi), 802.15.4 (LR-WPAN), and Bluetooth Low Energy (BLE).

2. Network Layer Protocols: These handle routing and addressing. IPv6 is the standard for IoT, with 6LoWPAN enabling IPv6 over low-power wireless personal area networks.

3. Transport Layer Protocols: These ensure end-to-end data delivery. TCP provides reliable, connection-oriented communication, while UDP is preferred for IoT due to its low overhead and suitability for real-time, loss-tolerant data.

4. Application Layer Protocols: These define how applications exchange data. Key protocols include:

• MQTT (Message Queuing Telemetry Transport): A lightweight publish-subscribe protocol ideal for resource-constrained devices.
• CoAP (Constrained Application Protocol): A web-transfer protocol designed for low-power devices, functioning similarly to HTTP but using UDP.
• HTTP/REST: Used for web-based services, though often too heavy for smaller sensors.
• AMQP (Advanced Message Queuing Protocol): Used for reliable, enterprise-grade messaging.

IoT Communication Models define how devices interact with the network:

• Request-Response Model: The client requests data from the server, and the server responds. This is the standard client-server architecture used in HTTP/REST.
• Publish-Subscribe Model: Decouples the sender (publisher) from the receiver (subscriber). Publishers send messages to a broker, which then distributes them to interested subscribers. This is highly scalable and used in MQTT.
• Push-Pull Model: Data producers push data into a queue, and consumers pull data from the queue. This decouples the timing of data production and consumption.
• Exclusive Pair Model: A bidirectional, fully duplex communication link established between a client and a server, remaining open until one party closes it, such as a TCP socket connection.