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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