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osi model osi model Presentation Transcript

  • – Layered Architecture
  • Lecture–Roadmap
    • Need of a Layered Architecture
    • OSI Model
      • 7 Layers of OSI Model
      • Functional Details of OSI Layers
        • Physical Layer
        • Data Link Layer
        • Network Layer
        • Transport Layer
        • Session Layer
        • Presentation Layer
        • Application Layer
  • Layered Architecture
    • Design Philosophy of Layered Architecture
      • The complex task of communication is broken into simpler sub-tasks or modules
      • Each layer performs a subset of the required communication functions
      • Each layer relies on the next lower layer to perform more primitive functions
      • Each layer provides services to the next higher layer
      • Changes in one layer should not require changes in other layers
      • Helps in troubleshooting and identifying the problem
  • An example Sending a letter
  • OSI Model
    • To standardize the design of communication
    • system, the ISO created the OSI model.
    • Open Systems Interconnection
    • Developed by the International Organization
    • for Standardization (ISO)
    • Contains Seven layers
    • It describes the functions to be performed at
    • each layer
  • OSI Model
    • ISO Established in 1947
    • ISO standard that covers all aspects of network communications is the Open Systems Interconnection ( OSI ) model.
    • First introduced in the late 1970s.
    • A layer model
    • Each layer performs a subset of the required
    • communication functions
    • Each layer relies on the next lower layer to
    • perform more primitive functions
    • Each layer provides services to the next
    • higher layer
    • Changes in one layer should not require
    • changes in other layers
  • ISO is the organization. OSI is the model. Note
  • OSI Model Application Presentation Session Transport Network Data Link Physical
  • Peer-to-Peer Process
  • An exchange using the OSI model
  • OSI Model – Physical Layer
    • Physical
      • Physical interface between devices
      • handles the transmission of bits over a
    • communications channel
      • Choice of Wired / wireless medium
      • Data is converted into signals
      • Includes voltage levels, connectors, media choice
      • modulation techniques
      • EIA/TIA-232, RJ45, NRZ.
  • Physical Layer
  • The physical layer is responsible for movements of individual bits from one hop (node) to the next. Note
  • OSI Model – Data Link Layer
    • • Data Link
    • – Transforms data into a frame
    • – Means of activating, maintaining and
    • deactivating a reliable link
    • – Error detection and control
    • – Flow Control
    • – Higher layers may assume error free
    • transmission
      • Examples :- Ethernet, Frame Relay, FDDI.
  • Data Link Layer
  • The data link layer is responsible for moving frames from one hop (node) to the next. Note
  • OSI Model – Network Layer
    • Network
    • – Transport of information
    • – Higher layers do not need to know
    • about underlying technology
    • – Responsible for creating, maintaining
    • and ending network connections
    • – Transfers a data packet from node to
    • node within the network .
    • – Routing
    • – Not needed on direct links
      • Examples :- IP, IPX, AppleTalk.
  • Network Layer
  • The network layer is responsible for the delivery of individual packets from the source host to the destination host. Note
  • Transport Layer
    • Transport
    • – Exchange of data between end
    • systems (end to end flow control)
    • – Error free
    • – In sequence
    • – Quality of service
    • Layer 4 protocols include TCP (Transmission Control Protocol) and UDP (User Datagram Protocol).
  • Transport Layer
  • The transport layer is responsible for the delivery of a message from one process to another. Note
  • OSI Model – Session Layer
    • Session
    • – Control of dialogues between
    • applications
    • Half Duplex
    • Full Duplex
    • – Synchronization Points (backup points)
      • Examples :- SQL, ASP(AppleTalk Session Protocol), NETBIOS, RPC, PAP.
  • The session layer is responsible for dialog control and synchronization. Note
  • OSI Model – Presentation Layer
    • Presentation
    • – Data formats and coding
    • – Data compression
    • – Encryption
      • Examples :- JPEG, MPEG, ASCII, EBCDIC, HTML.
  • The presentation layer is responsible for translation, compression, and encryption. Note
  • OSI Model – Application Layer
    • Application
    • – Layer where the application using the
    • network resides.
    • – Common network applications include
    • remote login
    • file transfer
    • e-mail
    • web page browsing etc.
    • – Means for applications to access OSI environment
  • The application layer is responsible for providing services to the user. Note
  • Summary of layers
  • OSI Layers
  • OSI Layers
  • The OSI Environment
  • The OSI Environment
  • TCP/IP Protocol Suit
    • TCP/IP suite is the set of protocols that implement the protocol stack on which the Internet runs. It is sometimes called the Internet Model.
    • This model consists of five ordered layers
    • In a protocol stack, each layer solves a set of problems involving the transmission of data, and provides a well-defined service to the higher layers
    • Developed by research foundation by US department of defense
  • Internet layers
  • TCP/IP Protocol Architecture Model
  • Some Protocols in TCP/IP Suite