search

Chapter 2 Network Models

Chapter 2 of Data Communications and Networking by Behrouz A. Forouzan, titled "Network Models", introduces the two primary networking models: the OSI (Open Systems Interconnection) model and the TCP/IP model. Here are detailed notes on this chapter:

hashtag
1. Layered Tasks

  • Concept of Layering: Layering simplifies networking tasks by dividing them into smaller, manageable processes.

  • Example: A postal system where tasks like writing, mailing, and delivering are carried out in layers, similar to how communication systems operate.

hashtag
2. The OSI Model

  • Introduction: The OSI model, established by the International Standards Organization (ISO), is a seven-layer framework that allows diverse systems to communicate.

  • Layered Architecture:

    • Communication happens between corresponding layers (peer-to-peer processes).

    • Data is passed through all layers from the application on the source to the destination, with headers and trailers added at each layer (encapsulation).

  • Layers of the OSI Model:

    1. Physical Layer: Deals with the transmission of raw bits over a communication channel.

    2. Data Link Layer: Responsible for error detection, flow control, and framing.

    3. Network Layer: Handles the logical addressing and routing of packets.

    4. Transport Layer: Ensures reliable process-to-process delivery of the message.

    5. Session Layer: Manages and controls the dialogs between computers.

    6. Presentation Layer: Transforms data into a format that the application layer can accept.

    7. Application Layer: Provides services directly to the end users such as file transfers, email, etc.

hashtag
3. The TCP/IP Model

  • Introduction: Unlike the OSI model, the TCP/IP model is used practically on the Internet.

  • Layers of the TCP/IP Model:

    1. Link Layer: Corresponds to the physical and data link layers of the OSI model.

    2. Internet Layer: Equivalent to the network layer of the OSI, handling logical addressing and routing.

    3. Transport Layer: Manages data delivery between processes.

    4. Application Layer: Handles high-level protocols such as HTTP, FTP, etc.

hashtag
4. Addressing

  • Different types of addresses used in network communications:

    1. Physical Address: The MAC (Media Access Control) address used for node-to-node communication.

    2. Logical Address: IP addresses used for source-to-destination delivery of data across multiple networks.

    3. Port Address: Identifies specific processes on the host device.

    4. Specific Address: User-friendly addresses like email addresses or URLs that are converted into port and logical addresses during communication.

hashtag
5. Summary

  • The OSI model, though theoretical, helps in understanding how communication protocols should function.

  • The TCP/IP model is practical and used widely in the Internet today.

  • Understanding both models is crucial for analyzing and working with modern networking technologies .

This chapter lays the foundation for further exploration of specific layers and their protocols in subsequent chapters.

Previouschapter 1NextChapter 3 Data and Signals

Last updated