Ref: https://learn.cantrill.io/courses/2022818/lectures/45700383

YouTube: https://www.youtube.com/watch?v=6hPMdpk9qA4

• Summary:
• Contents:

Computer Networking

• Local networking, e.g. Ethernet cables → data traffic between devices in a local NW
• Routing → data traffic across interconnected NWs
• Some concepts
  • Segmenting: chopping up data into smaller units
  • Port: number assigned to a connection
  • Session: awareness of a connection
  • Applications: SW programs, may communicate over a NW

OSI 7-Layer Model - Overview

Image Link: https://medium.com/software-engineering-roundup/the-osi-model-87e5adf35e10

• 💡 OSI = Open Systems Interconnection
• Networking Stack = all 7 layers of the OSI-model
  • Layers 1-3 = Media layers (deal with data moving from A→B)
  • Layers 4-7 = Host layers (deal with segmenting and recoupling data)
  • 💡 Every device that accesses a NW has (conceptually) this stack → Data moves from top layer down to physical layer, is transmitted over the physical medium, then moves up from physical layer up to top layer of receiver
• ‼️ OSI-Model is conceptual! Not all networking SW is implemented exactly like this!
  • 💡 But makes NWing much easier to understand
• Mnemonics (choose one to help memorize the 7 layers in order)
  • APSTNDP
    • All People Seem To Need Data Processing
  • PDNTSPA
    • Please Do Not Take Sales Person Advice
    • Please Do Not Transmit Secret Passwords Anywhere
    • People Don’t Need To See People Always