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1.1 1 OSI model

Open Systems Interconnection Model All People Seem to need Data Processing

Layer Num Layer name
Layer 7 Application
Layer 6 Presentation
Layer 5 Session
Layer 4 Transport
Layer 3 Network
Layer 2 Data Link
Layer 1 Physical

Layer 1 - Physical layer

  • The Physics of the network.
    • Signaling, cabling, connectors
    • This layer isn't about protocols
    • Wi-fi and bluetooth included
  • Physical Layer Problem?
    • Fix your cabling, punch-downs, etc
    • Run loopback tests, test/replace cable, swap adapter cards Cables , fiber, and the signal itself Electrical Signals
  • The basic network "language"
    • foundation of communication at the data link layer
  • Data Link Control (DLC) protocols
    • MAC ( Media Access Control)
  • Broken into 2 parts Data link Layer and the MAC layer
  • Referred to the "switching" layer
  • 00-21-70-0F-22-5A <----> 00-21-70-6F-06-F2 Frame, MAC Address, Extended Unique Identifier (EUI-48, EUI-64), Switch Ethernet

Layer 3 - Network layer

  • The "routing" layer
  • Internet Protocol
  • Fragments frames to traverse different networks
  • 192.168.0.1 <----> 10.22.253.7 *IP address, Router, Packet IP encapsulation

Layer 4 - Transport layer

  • The "post office" layer
    • parcels and letters
  • TCP (Transmission Control Protocol)
  • UDP (User Datagram Protocol) TCP segment, UDP datagram Transport - TCP encapsulation

layer 5 - session layer

  • Communication management between devices
    • start, stop, restart *Control Protocol, [[tunneling]] protocols Session - Link the presentation to the transport

layer 6 - presentation layer

  • Character encoding
  • Application encryption
  • Often combined with the application Layer *Application encryption (SSL/TLS) Presentation - SSL encryption

layer 7 - application layer