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Lesson 1 and 2 - Coggle Diagram

- - - - When machines are communicated they have to identify itself (IP address) and whats type of information is being shared (Port Number)
    - - Data moves around a network of networks (internet) via routers, in packets, using IP addresses.
      - Traffic passing between networks should be filtered using a firewall. A firewall operates at the network layer using a set of rules.
    - - Organises bits from physical layer into frames . Then exchanges frames using hardware address (MAC address) and basic error check the node was intact.
      - End Systems (Host Nodes): Computers, laptops, servers, VoIP phones, smartphones, printers
      - Intermediate Systems (Infrastructure Nodes): Switches, bridges.
      - Devices
        
        Network Interface Card (NIC)
        
        Bridge
        
        Switch
        
        Wireless access point (AP)
    - - Responsible for the transmission and reciept of bits of data from one node to another.
      - Types of transission media are cabled (bounded media) or wireless (unboaded media).
      - Devices that operate at the physical layer include:
        
        Transceiver
        
        Repeater
        
        Hub
        
        Media converter
        
        Modem
    - - Big Friendly Penguins Swim Deep Deep Deep
        
        Bits, Frames, Packets, Segments, Data, Data, Data
      - All People Seem To Need Data Processing
        
        Application, Presentation, Session, Transport, Network, Data Link, Physical
  - - - Netwok Protocol = set of rules for exchanging data in a structured format.
      - Network protocol has two principal functions
        
        Addressing - describing where data messages should go. AT each layer there are different mechanisms for identifying nodes and rules for how they can send and recive messages
        
        Encapsulation - describing how data messages should be packaged for transmission. It is like an envelope for a letter, with each layer requiring its own envolope. A
        
        When a message is sent from one device (node) to another it travels down the stack (OSI model layers) using the transmission media, and then passes up the stack on the receving node.
        
        At each level (except the physical layer), the sending node adds a head to the data payload, forming a chunk of data called a protcol data unit (PDU).