Overview
This lecture introduces the five-layer network model, explains the purpose of each layer, and describes the major protocols used at each stage of data communication.
The Five-Layer Network Model
- The networking model covered in this course consists of five layers.
- Each layer has a specific role in ensuring data is communicated accurately between devices.
Physical Layer
- The physical layer covers the physical devices, cables, connectors, and specifications for sending signals.
- It deals with the tangible aspects of networking, like wiring and signal transmission.
Data Link Layer
- The data link layer is responsible for interpreting signals to enable device communication.
- It introduces network protocols, most commonly Ethernet, but also includes wireless technologies.
- Defines how data is addressed and delivered on the same network link.
Network Layer
- The network layer connects different networks using devices called routers.
- It allows communication across multiple networks, creating internetworks (e.g., the internet).
- The main protocol at this layer is IP (Internet Protocol).
Transport Layer
- The transport layer ensures data is delivered to the correct application on each device.
- The main protocols are TCP (Transmission Control Protocol) and UDP (User Datagram Protocol).
- TCP ensures reliable data delivery; UDP does not provide reliability.
Application Layer
- The application layer contains protocols specific to the applications (such as web and email).
- Users interact directly or indirectly with protocols at this layer.
Key Terms & Definitions
- Physical Layer — defines hardware elements like cables and connectors, and how signals are transmitted.
- Data Link Layer — interprets signals and defines how data is delivered on a local network.
- Ethernet — a common data link protocol for wired networks.
- Network Layer — connects multiple networks using routing, primarily using the IP protocol.
- IP (Internet Protocol) — delivers data between networks.
- Transport Layer — directs data to correct applications (e.g., TCP, UDP).
- TCP (Transmission Control Protocol) — ensures reliable delivery of data.
- UDP (User Datagram Protocol) — provides faster, but unreliable, data delivery.
- Application Layer — handles protocols used by end-user applications (e.g., web, email).
Action Items / Next Steps
- Review key characteristics and functions of each layer.
- Prepare to learn the differences between TCP and UDP in upcoming lessons.