Reference_model on computer network.pptx
- 1. OSI and TCP/IP Model Rakibul Hassan Lecturer Dept. of ECE, RUET
- 2. Reference Model ● The OSI Reference Model ○ Open Systems Interconnection ○ Not a practical model, just a concept ● The TCP/IP Reference Model ○ Transmission Control Protocol/Internet Protocol ○ Practical model ● Both are layered models ○ A layer is created where a different abstraction is needed. ○ Each layer should perform a well-defined function. 2
- 3. OSI Model OSI 7 Application 6 Presentation 5 Session 4 Transport 3 Network 2 Data Link 1 Physical “Please Do Not Throw Sausage Pizza Away!” 3
- 4. OSI Model OSI 7 Application 6 Presentation 5 Session 4 Transport 3 Network 2 Data Link 1 Physical OSI 7 Application 6 Presentation 5 Session 4 Transport 3 Network 2 Data Link 1 Physical Supports the communication between applications over the network Presents data to the receiver in a form it recognizes Establishes a connection and terminates it when no longer required Acknowledges the flow of data including re-transmission where required (Handles segments) Adds the appropriate network addresses to packets (Handles packets) Adds the MAC addresses to frames (Handles frames) Transmits the data on the medium (Handles Bits) 4
- 5. OSI and TCP/IP Models OSI TCP/IP 7 Application Application 6 Presentation 5 Session 4 Transport Transport 3 Network Internet 2 Data Link Network Access/link layer 1 Physical 5
- 6. OSI and TCP/IP Models - PDU OSI TCP/IP Protocol Data Unit 7 Application Application Data 6 Presentation 5 Session 4 Transport Transport Segments 3 Network Internet Packets 2 Data Link Network Access Frames 1 Physical Bits 6
- 7. Application Layer OSI TCP/IP Function 7 Application Application - Provides a set of interfaces for sending and receiving applications to gain access to and use network services - Deals with networking applications. Example: 6 Presentation 5 Session 4 Transport Transport 3 Network Internet 2 Data Link Network Access 1 Physical • Web browsers • Email • Facebook 7
- 8. Application Layer OSI TCP/IP Function 7 Application Application - Responsible for presenting the data in the required format - Data is formatted, converted, encrypted/decrypted compressed/ decompressed and sent or presented to the user 6 Presentation 5 Session 4 Transport Transport 3 Network Internet 2 Data Link Network Access 1 Physical 8
- 9. Application Layer OSI TCP/IP Function 7 Application Application - Establishes, manages, and terminates sessions between two communicating hosts. - Coordinates communication between systems - Organizes their communication by offering three different modes 6 Presentation 5 Session 4 Transport Transport 3 Network Internet 2 Data Link Network Access 1 Physical • Simplex • Half-duplex • Full-duplex 9
- 10. Transport Layer OSI TCP/IP Function 7 Application Application - Facilitates end-to-end communications between multiple applications simultaneously (ports) - Reliable and unreliable end-to-end data transport and data stream services (TCP, UDP, SCTP) - Other features of this layer: 6 Presentation 5 Session 4 Transport Transport 3 Network Internet 2 Data Link Network Access 1 Physical 10 • Sequencing • Acknowledgement • Retransmission • Flow Controls
- 11. Network Layer OSI TCP/IP Function 7 Application Application - Provide host addressing (IP) - Choose the best path to the destination network (Routing) - Switch packets out of the correct interface (Forwarding) - Maintain quality of service (QoS) - Connectionless end-to-end networking 6 Presentation 5 Session 4 Transport Transport 3 Network Internet 2 Data Link Network Access 1 Physical 11
- 12. Data Link Layer OSI TCP/IP Function 7 Application Application - Performs Physical Addressing - 2 sublayers: - Logical Link Control (LLC) provides services to the upper layers - Media Access Control (MAC) defines how devices access the medium - Error Detection and Checking 6 Presentation 5 Session 4 Transport Transport 3 Network Internet 2 Data Link Network Access 1 Physical 12
- 13. Physical Layer OSI TCP/IP Function 7 Application Application - This is the physical media through which the data, represented as electronic signals, is sent from the source host to the destination host. - Move bits between devices - Encoding 6 Presentation 5 Session 4 Transport Transport 3 Network Internet 2 Data Link Network Access 1 Physical 13
- 14. Encapsulation and Decapsulation OSI TCP/IP 7 Application Application 6 Presentation 5 Session 4 Transport Transport 3 Network Internet 2 Data Link Network Access 1 Physical Encapsulation Decapsulation 14
- 15. Encapsulation Application Data Transport Segments Internet Packets Network Access Frames Bits Data Data Transport Header D D T T D T D T D T D T Data Transport Header Network Header Data Transport Header Network Header Frame Trailer Frame Header 1111010010101011011010101010101010111 15
- 16. 16 Acknowledgement 1. Slides from Tazeen Tasneem, Lecturer, Dept. of CSE, EUB