Net1

• Explaining the OSI and TCP/IP Models

  1. Explanation of OSI Model Layers

  2. Explanation of the TCP/IP Suite
• Explanation of OSI Model Layers

  1. Explain devices, applications, protocols, and services at their appropriate OSI layers

  2. Explain the concepts and characteristics of routing and switching
• Network Boundaries: Two or more computer systems linked by transmission media to share information
• Network services provided


  • Sharing data and resources
  • Email and database applications
  • Web applications and social networking
  • Voice and multimedia conferencing
  • Local Area Network (LAN)
  • Wide Area Network (WAN)
• Open Systems Interconnection (OSI) Model

  A conceptual framework that standardizes the functions of a telecommunication or computing system into seven abstraction layers
• Protocol Data Units (PDUs)

  Rules for exchanging data, addressing, encapsulation, header, payload
• Layer 1 (Physical)


  Nodes, stations, hosts, transmission media, physical topology
• Layer 2 (Data Link)


  Local network devices, organizing bits into frames, error detection, flow control, media access rules/logical topology
• Layer 3 (Network)


  Moving data around a network of networks, logical addressing, routing, route discovery, path selection
• Layer 4 (Transport)


  Multiplexing, de-multiplexing, reliable delivery, connection establishment, acknowledgements, segmentation, flow control
• Session and Presentation Layers


  Identifying message sequences, dialog control, character set conversion, compression, encryption
• Layer 7 (Application)


  Top layer providing communications protocols and interfaces for software processes running on different hosts
• Divisions between upper layers are less important in real-world protocols
• APIs can be written for any layer of the stack
• Network card drivers (e.g., NDIS) at layer 2 (Data Link)
• Sockets/WinSock at layer 5 (Session)
• High-level API functions (file transfer, email, web browsing, and DNS) at layer 7
• OSI Model Summary
• Image © 123RF.com
• Discussing OSI Model Layers
• What OSI model layer transmits bits from one device to another and modulates the transmission stream over a medium?
• Physical
• Transport
• Data Link
• Network
• At which OSI layer do programs on a network node access network services?
• Application
• Which OSI layer is responsible for establishing reliable connections between two devices?
• Presentation
• Which OSI layer packages bits of data from the Physical layer into frames?
• Session
• At which sublayer of the OSI model do network adapter cards operate?
• Data Link layer
• What component is responsible for translating the computer's digital signals into electrical or optical signals that travel on network cable?
• A transceiver
• True or False? The Session layer is responsible for passing data to the Network layer at the lower bound and the Presentation layer at the upper bound.
• False. The Session layer is between the Transport and Presentation layers
• Which OSI layer handles the concept of logical addressing?
• The Network layer
• At which OSI layer is the concept of a port number introduced?