Network Models and Types of Networks Summary (copy)

Protocol and Reference Models

  • Networking uses protocol and reference models for communication.

  • Protocol model: Matches the structure of a protocol suite (e.g., TCP/IP).

  • Reference model: Provides consistency across network protocols and services.

  • OSI model: Understand network communication.

  • TCP/IP model: Understand implementation in current networks.

The ISO OSI Model

  • Developed by the International Organization for Standardization (ISO) in 1977.

  • Also known as the OSI model or OSI stack.

  • Has seven layers:

    • Application: Network services for end-user applications.

    • Presentation: Data format, encryption.

    • Session: Establishes, manages, and terminates sessions.

    • Transport: Defines and numbers data segments, reassembles data.

    • Network: Creates and addresses packets for end-to-end delivery.

    • Data Link: Creates and addresses frames for host-to-host delivery on LANs and between WAN devices.

    • Physical: Transmits binary data over media; defines media specifications.

TCP/IP Protocol Suite

  • Defines four communication functions that protocols perform.

  • Developed using Request for Comments (RFC) documents.

Protocol Data Units and Encapsulation

  • Protocol data unit (PDU): The form data takes at each layer.

  • Packet: General term for PDUs.

  • Encapsulation: Adding control information as data passes through layers.

  • Decapsulation: Removing extra information at the destination.

  • Headers and trailers contain control information for network devices and receivers.

Defining a Network

  • Computer network: Connection between endpoints for information exchange and resource sharing.

  • Networks are defined based on purpose and/or size.

Networks Defined by Geography

  • Classified by geographic dispersion, number of users, and types of services.

  • Types of Networks:

    • Local Area Network (LAN): Limited geographic area, private, internal communications.

    • Wide Area Network (WAN): Connects geographically distant LANs (e.g., the Internet).

    • Metropolitan Area Network (MAN): Connects LANs within a common geographic area (city).

    • Personal Area Network (PAN): Small scale, revolves around one person.

Network Topologies

  • Defines how devices are connected and the layout of the network.

  • Physical topology: Physical layout of devices and media.

  • Logical topology: How the medium is accessed for sending data.

  • Common LAN physical topologies: Bus, Star, Ring, Mesh, Extended star, Hierarchical.