OSI 7 Layer Model
- 1. WELCOME TO OURWELCOME TO OUR PRESENTATIONPRESENTATION 1
- 4. INTRODUCTIONINTRODUCTION International standard organization (ISO) established a committeeInternational standard organization (ISO) established a committee in 1977 to develop an architecture for systemsin 1977 to develop an architecture for systems communication.communication. Open System Interconnection (OSI) reference model is theOpen System Interconnection (OSI) reference model is the result of this effort.result of this effort. This model allows any two different systems to communicateThis model allows any two different systems to communicate regardless of their underlying architecture.regardless of their underlying architecture. 4
- 5. CONT..CONT.. The OSI model describes how data flows from one computer, throughThe OSI model describes how data flows from one computer, through a network to another computer.a network to another computer. The OSI model is not a protocol; it is a model for understanding andThe OSI model is not a protocol; it is a model for understanding and designing a network architecture that is flexible and robust.designing a network architecture that is flexible and robust. The OSI model consists of seven separate but related layers, each ofThe OSI model consists of seven separate but related layers, each of which defines a part of the process of moving information across awhich defines a part of the process of moving information across a network.network. 5
- 6. 6 APPLICATIONAPPLICATION PRESENTATIONPRESENTATION SESSIONSESSION TRANSPORTTRANSPORT NETWORKNETWORK DATA LINKDATA LINK PHYSICALPHYSICAL APPLICATIONAPPLICATION PRESENTATIONPRESENTATION SESSIONSESSION TRANSPORTTRANSPORT NETWORKNETWORK DATA LINKDATA LINK PHYSICALPHYSICAL MIDDLE LAYER MIDDLE LAYER HIGHER LAYER HIGHER LAYER Application to Application Application to Application Application to Application Process to Process LOWER LAYER LOWER LAYER Hop to Hop Switch Hop to Hop Physical Medium Hub and Repeater Router Source to Destination Source to Destination OSI Model's 7 LayersOSI Model's 7 Layers
- 7. HOST AND MEDIA LAYERHOST AND MEDIA LAYER 7
- 8. PHYSICAL LAYERPHYSICAL LAYER One of the major function of the physical layer is to move data in the form of electromagnetic signals acrossOne of the major function of the physical layer is to move data in the form of electromagnetic signals across a transmission medium.a transmission medium. Its responsible for movements of individual bits from one hop (Node) to next.Its responsible for movements of individual bits from one hop (Node) to next. Both data and the signals can be eitherBoth data and the signals can be either analoganalog oror digitaldigital.. Transmission media work by conducting energy along a physical path which can be wired or wirelessTransmission media work by conducting energy along a physical path which can be wired or wireless Concerned:Concerned: Physical characteristics of interface and mediumPhysical characteristics of interface and medium (Transmission medium)(Transmission medium) Representation of bitsRepresentation of bits (stream of bits (0s or 1s) with no interpretation and encoded into signals)(stream of bits (0s or 1s) with no interpretation and encoded into signals) Data rateData rate (duration of a bit, which is how long it last)(duration of a bit, which is how long it last) Synchronization of bitsSynchronization of bits (sender and receivers clock must be synchronized)(sender and receivers clock must be synchronized) Line configurationLine configuration (Point-to-Point, Point-to-Multipoint)(Point-to-Point, Point-to-Multipoint) Physical topologyPhysical topology Transmission modeTransmission mode (Simplex, half duplex, full duplex)(Simplex, half duplex, full duplex) 8 10101000000010111110 From data link layer 10101000000010111110 To data link layer Physical layer Physical layer Transmission medium
- 9. DATA LINK LAYERDATA LINK LAYER (HOST TO HOST)(HOST TO HOST) Data link layer is responsible for moving frames from one hop (Node) to the next.Data link layer is responsible for moving frames from one hop (Node) to the next. Concerned:Concerned: FramingFraming (stream of bits into manageable data units)(stream of bits into manageable data units) Physical addressingPhysical addressing (MAC Address)(MAC Address) Flow ControlFlow Control (mechanism for overwhelming the receiver)(mechanism for overwhelming the receiver) Error ControlError Control (trailer, retransmission)(trailer, retransmission) Access ControlAccess Control (defining master device in the same link)(defining master device in the same link) 9 DataH2 T2 From network layer DataH2 T2 To network layer To physical layer From physical layer Data link layer Data link layer
- 10. NETWORK LAYERNETWORK LAYER (SOURCE TO DESTINATION)(SOURCE TO DESTINATION) • The network layer is responsible for the delivery of individual packets from theThe network layer is responsible for the delivery of individual packets from the source host to the destination host.source host to the destination host. • Concerned:Concerned: • Logical addressingLogical addressing (IP Address)(IP Address) • RoutingRouting (Source to destination transmission between networks)(Source to destination transmission between networks) 10 DataH3 Packet From transport layer To data link layer DataH3 Packet To transport layer From data link layer Network layer Network layer
- 11. TRANSPORT LAYERTRANSPORT LAYER (PROCESS TO PROCESS)(PROCESS TO PROCESS) The transport layer is responsible for the delivery of a message from one process toThe transport layer is responsible for the delivery of a message from one process to anotheranother Concerned:Concerned: Service-point addressing (Port address)Service-point addressing (Port address) Segmentation and reassembly (Sequence number)Segmentation and reassembly (Sequence number) Connection control (Connectionless or connection oriented)Connection control (Connectionless or connection oriented) Flow control (end to end)Flow control (end to end) Error Control (Process to Process)Error Control (Process to Process) 11 SegmentsSegments DataH4 From session layer To network layer Transport layer DataH4 DataH4 SegmentsSegments DataH4 From session layer From network layer Transport layerDataH4 DataH4
- 12. SESSION LAYERSESSION LAYER (DIALOG INITIATION)(DIALOG INITIATION) The session layer is responsible for dialog control and synchronizationThe session layer is responsible for dialog control and synchronization Concerned:Concerned: Dialog Control (Half Duplex/Full duplex)Dialog Control (Half Duplex/Full duplex) Synchronization (Synchronization points, process inline within same pageSynchronization (Synchronization points, process inline within same page)) 12 DataH5 From Presentation layer To transport layer Data Data Syn Syn Syn DataH5 To Presentation layer From transport layer Data Data Syn Syn Syn Session layer Session layer
- 13. PRESENTATION LAYERPRESENTATION LAYER (DEPENDENCY)(DEPENDENCY) The presentation layer is responsible for translation, compression and encryptionThe presentation layer is responsible for translation, compression and encryption Concerned:Concerned: Translation (interoperability between different encoding system)Translation (interoperability between different encoding system) Encryption (Privacy schemes)Encryption (Privacy schemes) Compression (data compression)Compression (data compression) 13 DataH6 From application layer To session layer DataH6 To application layer From session layer presentation layer presentation layer
- 14. APPLICATION LAYERAPPLICATION LAYER (USER LEVEL SERVICE)(USER LEVEL SERVICE) The application layer is responsible for providing services to the user.The application layer is responsible for providing services to the user. Concerned:Concerned: Network virtual terminal (Software)Network virtual terminal (Software) File transfer, access and managementFile transfer, access and management Mail servicesMail services Directory services (access to distributed database sources for global information about variousDirectory services (access to distributed database sources for global information about various objects and servicesobjects and services)) 14 DataH7 USER (Human or Program) To presentation layer DataH7 Application layer Application layer Message Message X.500 FTAM X.400 X.500 FTAM X.400 From presentation layer USER (Human or Program)