OSI Layers Overview

OSI Layers Overview

The OSI (Open Systems Interconnection) model is a 7-layered framework for designing and implementing computer networks.

Layer 7: Application Layer

• Provides services to end-user applications
• Functions:
  • Process-to-process communication
  • Data formatting and encryption
• Protocols:
  • HTTP, FTP, SMTP, DNS

Layer 6: Presentation Layer

• Converts data into a format that can be understood by the receiving device
• Functions:
  • Data compression and encryption
  • Data formatting
• Protocols:
  • SSL, TLS

Layer 5: Session Layer

• Establishes, manages, and terminates connections between applications
• Functions:
  • Session establishment and termination
  • Dialogue management
• Protocols:
  • NetBIOS, SSH

Layer 4: Transport Layer

• Provides reliable data transfer between devices
• Functions:
  • Segmentation and reassembly
  • Error detection and correction
• Protocols:
  • TCP, UDP

Layer 3: Network Layer

• Routes data between networks
• Functions:
  • Routing and congestion control
  • Addressing and packet forwarding
• Protocols:
  • IP, ICMP, IGMP

Layer 2: Data Link Layer

• Provides error-free transfer of data frames between nodes
• Functions:
  • Framing and error detection
  • Flow control and multiplexing
• Protocols:
  • Ethernet, Wi-Fi, PPP

Layer 1: Physical Layer

• Defines the physical means of transmitting data
• Functions:
  • Bit transmission and reception
  • Cable specification and wireless transmission
• Protocols:
  • RJ-45, Wi-Fi, Bluetooth

OSI Layers Overview

• The OSI model is a 7-layered framework for designing and implementing computer networks.

Layer 7: Application Layer

• Provides services to end-user applications, enabling process-to-process communication.
• Performs data formatting and encryption.
• Supports protocols such as HTTP, FTP, SMTP, and DNS.

Layer 6: Presentation Layer

• Converts data into a format that can be understood by the receiving device.
• Performs data compression and encryption.
• Performs data formatting.
• Supports protocols such as SSL and TLS.

Layer 5: Session Layer

• Establishes, manages, and terminates connections between applications.
• Manages session establishment and termination.
• Manages dialogue between applications.
• Supports protocols such as NetBIOS and SSH.

Layer 4: Transport Layer

• Provides reliable data transfer between devices.
• Performs segmentation and reassembly of data.
• Performs error detection and correction.
• Supports protocols such as TCP and UDP.

Layer 3: Network Layer

• Routes data between networks.
• Performs routing and congestion control.
• Manages addressing and packet forwarding.
• Supports protocols such as IP, ICMP, and IGMP.

Layer 2: Data Link Layer

• Provides error-free transfer of data frames between nodes.
• Performs framing and error detection.
• Performs flow control and multiplexing.
• Supports protocols such as Ethernet, Wi-Fi, and PPP.

Layer 1: Physical Layer

• Defines the physical means of transmitting data.
• Performs bit transmission and reception.
• Specifies cable and wireless transmission.
• Supports protocols such as RJ-45, Wi-Fi, and Bluetooth.