osi-model

Introduction:

• The OSI (Open Systems Interconnection) model is a conceptual framework used to understand and standardize how different networking protocols and technologies communicate in a network.

• It consists of seven distinct layers, each with its own unique function and purpose.

• The OSI model was developed by the International Organization for Standardization (ISO) to facilitate interoperability and communication between different network devices and systems.

• The OSI model describes 7 layers that computer systems use to communicate over a network , Conceptual model , not in use (Theoretical)

Seven Layers of the OSI Model:

Acronym for OSI model:Please do not take sausage pizza away

1. Physical Layer:

   • This layer deals with the physical medium and transmission of raw bits over a physical link.

   • It specifies the hardware characteristics, such as cables, connectors, and network interface cards.

   • Key components: voltage levels, cable types, and bit rate.

2. Data Link Layer:

   • Responsible for framing, addressing, and error detection on the physical layer.

   • It organizes data into frames and ensures reliable data transfer between adjacent nodes.

   • Key components: MAC (Media Access Control) addresses, Ethernet, and framing.

3. Network Layer:

   • Focuses on routing and forwarding data between different networks and subnets.

   • It uses logical addressing (e.g., IP addresses) to determine the best path for data packets.

   • Key components: IP addresses, routers, and routing protocols (e.g., OSPF, BGP).

4. Transport Layer:

   • Manages end-to-end communication and data segmentation.

   • It provides error detection, flow control, and data reassembly.

   • Key components: TCP (Transmission Control Protocol) and UDP (User Datagram Protocol).

5. Session Layer:

   • Establishes, maintains, and terminates communication sessions between devices.

   • It controls the dialogue and ensures data synchronization between applications.

   • Key components: Session initiation, termination, and management.

6. Presentation Layer:

   • Responsible for data translation, encryption, and compression.

   • It ensures that data is presented in a readable format for the application layer.

   • Key components: Data encryption, character encoding, and data compression.

   • Data format : HTML , XML , jpg

   • Encryption : SSL

7. Application Layer:

   • This is the topmost layer that interacts directly with end-user applications.

   • It provides services and protocols that allow applications to communicate over the network.

   • Key components: HTTP, FTP, SMTP, and application-specific protocols.