Operating System

Chapter 1

Network Layers

OSI stands for Open System Interconnection

  • Layer 1: Physical connection [fiber, wireless, hubs]
  • Layer 2: Frames [ethernet, PPP (Point-to-Point Protocol), switch, bridge]
  • Layer 3: Packets [IP (Internet Protocol), ICMP (Internet Control Message Protocol), IPSec (Internet Protocol Security), IGMP (Internet Group Management Protocol)]
  • Layer 4: End-to-end connection [TCP (Transmission Control Protocol), UDP (User Diagram Protocol)]
  • Layer 5: Sync & send to port [API, socket]
  • Layer 6: Syntax [SSL (Secure Sockets Layer), JPEG (Joint Photographic Experts Group), MPEG (Moving Pictures Experts Group)]
  • Layer 7: End User [HTTP (Hyper Text Transfer Protocol), DNS (Domain Name System)]

TCP/IP stands for Transmission Control Protocol/Internet Protocol

  • Application Layer corresponds to layer numbers 5,6 & 7 of OSI Model
  • Transport Layer corresponds to layer numbers 4 of OSI Model
  • Internet Layer corresponds to layer numbers 3 of OSI Model
  • Network Interface Layer corresponds to layer numbers 2 & 1 of OSI Model