OSI Model PDF

OSI Model Prepared by: Pr RIAHLA 1  Problem Each manufacturer developed its own network solutions and communication protocols. IBM SNA DEC DECNET NOVELL N...

OSI Model Prepared by: Pr RIAHLA 1  Problem Each manufacturer developed its own network solutions and communication protocols. IBM SNA DEC DECNET NOVELL Netware IPX/SPX Microsoft NETBIOS Apple APPLE TALK VAX VMS Proprietary networks Prepared by: Pr RIAHLA 2  Proprietary networks Prepared by: Pr RIAHLA 3  OSI Model The OSI (Open System Interconnection) standard is established by the International Organization for Standardization (ISO). Prepared by: Pr RIAHLA 4  Open System Definition An open system is a computer, terminal, network, smartphone, chip, sensor, switch, router, and more. Any device that follows this standard can share information: With other heterogeneous devices designed by different manufacturers. Prepared by: Pr RIAHLA 5  OSI layers Application Application Presentation management. The OSI model Session consists of 7 Transport layers, each layer solving a specific Network Transport problems. management. Data link Physical Prepared by: Pr RIAHLA 6  OSI Architecture  Each layer N:  Provides a service (N)  Uses a protocol (N)  Has a service access point (N-SAP) Each layer uses a protocol and provides services to neighboring layers. Prepared by: Pr RIAHLA 7  Architecture du modèle OSI Protocol Application Application Service Presentation Presentation Service Session Session Service Transport Transport Service Network Network Service Data link Data link Service Physical Physical 8  Physical layer The physical layer handles aspects related to:  Transmission of raw bits over a physical medium  Hardware components like cables, switches, and network interface cards  Electrical, optical, or radio signals  Throughput (debit) , signal modulation, and synchronization The physical layer only transmits raw bits without any specific meaning. Prepared by: Pr RIAHLA 9  Data Link Layer  Packaging raw bits from the physical layer into data frames.  Error detection and correction that may occur during transmission.  Flow control: Managing the pace (rythme) of data transmission to prevent congestion between sender and receiver. Prepared by: Pr RIAHLA 10  Data Link Layer  MAC addressing: Assigning a unique Media Access Control address to each device for proper identification on the network.  Media access control: Governing how devices share the transmission medium, using protocols like Ethernet or Wi-Fi. handles communication only between adjacent network (neighbors) nodes. Prepared by: Pr RIAHLA 11  Network layer Routing No IP Routing No IP Routing  Routing: finds the best path for data across networks.  Logical addressing: Assigning addresses to devices for identification and communication across different networks  Handling traffic congestion: Managing network congestion by controlling data flow. Prepared by: Pr RIAHLA 12  Network layer Routing packets Prepared by: Pr RIAHLA 13  Network layer Fragmentation and reassembly: Splits large packets into smaller fragments and reassembles them at the destination. How to find the desired application? Prepared by: Pr RIAHLA 14  Transport layer  Handles communications between end systems.  Segmentation: Dividing large messages into smaller segments.  Flow control: Regulating the data transmission rate between sender and receiver to prevent congestion. Prepared by: Pr RIAHLA 15  Transport layer  Connection management: Establishing, maintaining, and closing connections between devices.  Reliability: Ensuring that data is delivered accurately and in the correct order,  Addressing Applications (Port Numbers) Prepared by: Pr RIAHLA 16  Transport layer Multiplexing DemMultiplexing Prepared by: Pr RIAHLA 17  Transport layer how To manage and control the dialog between two devices or systems ? Prepared by: Pr RIAHLA 18  Session Layer Synchronization (User, Password, etc. )  Establishing, Maintaining, closing (properly) and Synchronization (Resynchronization) sessions  Managing Dialogs (half-duplex or full-duplex) Prepared by: Pr RIAHLA 19  Session Layer What data type to send? Prepared by: Pr RIAHLA 20  Presentation Layer It represents data independently of computers and operating systems, and includes services like: Data Translation (Converts data between different formats used by applications): Data Formatting Data Encryption/Decryption Data Compression/Decompression Prepared by: Pr RIAHLA 21  Presentation Layer Data Translation: Converts data between different formats used by applications. For example, translating between character encoding formats like ASCII, EBCDIC, or Unicode. Data Encryption/Decryption: Encrypts data for secure transmission and decrypts it upon receipt to protect information during communication. Data Compression/Decompression: Compresses data to reduce its size for efficient transmission, and decompresses it at the receiving end to restore the original data format. Data Formatting: Ensures that data structures (e.g., file formats like JPEG, PNG, or MP4) are in the correct format to be interpreted by the receiving system. Prepared by: Pr RIAHLA 22  Presentation layer But who will benefit from all this? Prepared by: Pr RIAHLA 23  Application layer Interface between the end-user and the network It provides various services and protocols that applications use to communicate over a network Examples of protocols: HTTP (Hypertext Transfer Protocol) for web browsing FTP (File Transfer Protocol) for transferring files SMTP (Simple Mail Transfer Protocol) for sending emails DNS (Domain Name System) for resolving domain names to IP addresses Prepared by: Pr RIAHLA 24  Application layer Prepared by: Pr RIAHLA 25  OSI Model Summary Prepared by: Pr RIAHLA 26  Number of Layers per Device. Communication Equipement: 07 Layers Interconnexion Equipement: