OSI‐Model

The provided image illustrates the 7 layers of the Open Systems Interconnection (OSI) model—a conceptual framework describing the process of data transmission across networks.

Layer 1: Physical

This layer manages the physical transmission of data through network mediums like copper wire, fiber optic cables, or radio waves. Devices within this layer include routers, switches, and hubs.

Layer 2: Data Link

Responsible for framing data into packets and ensuring reliable transmission over the network medium, this layer also handles error detection and correction. Protocols in this layer encompass Ethernet, Wi-Fi, and PPP.

Layer 3: Network

Handling packet routing within the network, this layer provides logical addressing for device identification. Protocols here include IP and ICMP.

Layer 4: Transport

Facilitating end-to-end communication between applications, this layer ensures the reliable delivery of packets and controls data flow. Protocols like TCP and UDP operate at this level.

Layer 5: Session

In charge of establishing, managing, and terminating sessions between applications, this layer incorporates protocols such as HTTP, FTP, and Telnet.

Layer 6: Presentation

This layer translates data into a format understandable by the receiving application, managing data encryption and decryption. SSL/TLS and MPEG are examples of protocols in this layer.

Layer 7: Application

Providing network services to applications, this top layer includes protocols like HTTP, FTP, and SMTP.

Examples of devices and protocols at each layer:

Layer	Device	Protocol
Physical	Router, switch, hub	Ethernet, Wi-Fi, PPP
Data Link	Ethernet card, Wi-Fi adapter	Ethernet, Wi-Fi, PPP
Network	Router	IP, ICMP
Transport	Host	TCP, UDP
Session	Web browser, FTP client	HTTP, FTP
Presentation	Web browser, FTP client	SSL/TLS, MPEG
Application	Web browser, FTP client	HTTP, FTP, SMTP