networks, connections and protocols

Cards (42)

  • Network
    A group of connected things or people
  • Graph
    A diagram that is used to show the connections between things or people in a network
  • Edges
    The lines on a graph that are used to show the connections between the nodes
  • Nodes are circles on a graph and these represent the item that forms the connection. Nodes can be used to represent many thing
  • Computer network
    Two or more computers connected together, sharing resources
  • Client
    The client requests data, information and actions from the server
  • Server
    The server responds to requests from the client
  • Peer to peer
    A type of connection used in a network. Each device in this network have equal responsibility. They can act as both client and server
  • Local area network (LAN)

    • Small geographical area
    • Network hardware owned by individual or company
    • Connected computers (e.g. Ethernet and Wi-Fi connectivity)
  • Wide Area Network (WAN)
    • Large geographical area
    • Connecting multiple LANs together
    • Network hardware between sites may need to be hired
  • Advantages & disadvantages of WAN are the same as LAN but now apply to multiple sites
  • Star network topology
    • Once central hub / switch / router / server
    • All devices connected to this central point
  • Full mesh network topology

    • Every device is connected to every other device
  • Partial mesh network topology

    • Multiple routes exist between different devices
    • However, every device is not connected to every single other device
  • Partial mesh network topology
    A compromise solution which lowers the amount of hardware needed compared to a full mesh network
  • NIC (Network Interface controller)
    connects device to wired/wireless network
  • WAP
    Wireless access point: allows WAP devices to connect to network (using radio waves). Less cables but slower than wired connection + more security risk
  • Switch/Hub
    Directs, routes packets on LAN between devices using MAC addresses
  • Router
    Directs/ routes packets on a WAN, connects LANs, uses IP addresses to connect to other routers
  • Cables
    Ethernet, copper cables, UTP (unshielded twisted pair), fibre optic. Copper cheap, more interference
  • Factors that affect the performance of networks
    • Topology of the network
    • Number of users
    • Bandwidth
    • Transmission media
  • Bandwidth
    Amount of data it can send and receive at one time, bits per second
  • Transmission media
    Bandwidth: fibre optic > ethernet > wireless connection (e.g. Wi-Fi)
  • Client-server
    • A server controls – access/security of file storage, access to the internet, backups of data
    • A client makes requests to the server for data and connections
    • Expensive to set up/maintain
    • Reliance on central server if it fails, all access could be lost for all devices
  • Peer-to-peer
    • All peers on the network are equal
    • Peers serve their own files to each other
    • Each peer is responsible for its own security/backup
  • Ethernet
    • Used for communicating on a wired LAN
    • Includes associated protocols
    • Reliable, error free, fast communication between 2 points
    • Originally used in old style bus networks
    • Still used in more modern star and mesh networks
    • Data transmitted in frames
    • Users location limited by need for a physical connection
    • A set up relying on ethernet relies on physical hardware which will affect cost
  • Wireless networks
    • Very short rangefor connecting a wireless keyboard to a computer or wireless headphones to a mobile phone
    • Wi-Fi is a common standard for wireless networks: Users can move around freely, Easier to set up, and less expensive, Convenient to use, Can handle large numbers of users, Transfer of information to social media is much easier, Speeds are slower than wired networks, Relies on signal strength to the wireless access point (WAP), Signal can be obstructed, Less secure than wired networks
  • Bluetooth
    • It is ideal for connecting personal devices
    • Short range - around 10 metres
    • Very low power consumption compared to Wi-Fi
  • Wireless Encryption
    • Data must be encrypted to be secure.
    • Data is scrambled into a cipher text using a "master key" created from the SSID of the network and the password. Data is decrypted by the receiver using the same master key, so this key is not transmitted. Protocols used for wireless encryption include WEP, WPA and WPA2. A handshaking protocol is used to ensure that the receiver has a valid master key before transmission to the device begins.
  • MAC addressing
    • Used to route frames on a local area network (LAN)
    • Each MAC address is unique to every network interface card
  • IP addressing
    • Used to route packets on a WAN
    • Two versions of IP addresses - IPv4, IPv6
    • IPv4 address: 32 bits, 4 numbers separated by periods (.), each number in range 0-255, Eg: 69.89.31.266
    • A router will have a unique WAN facing IP address as another device on another LAN
    • This enabled a LAN device to have the same IP address as another device on another LAN
    • IPv4 being replaced by IPv6 because unique static addresses are running out
    • IPv6 address: 128-bits, 8 groups separated by colons (:), each group made up of 4 hex values representing 16-bits, Eg: 2001:0db8:85a3:0000:0000:8a2e:0370:7334
  • Layering
    • Dividing complex task of networking into smaller, simpler tasks that work with each other. The hardware/software for each layer has a defined responsibility. Each layer provides service to the layer above it.
    • Advs include: Reduced complexity of problem into small sub-problems, Devices can be manufactured to operate at particular layer, products from different vendors work together
  • Common protocols
    • TCP/IP - Transmission control protocol/internet protocol
    • HTTP - Hypertext transmission protocol
    • HTTPS - Hypertext transmission protocol secure
    • FTP - File transfer protocol
    • POP - Post office protocol
    • IMAP - Internet message access protocol
    • SMTP - Simple mail transfer protocol
  • TCP
    Transmission control protocol: provides an error free transmission between two routers
  • IP
    Internet protocol: routes packets across a wide area network, along with TCP it makes up the TCP/IP protocol stack
  • HTTP
    Hypertext transfer protocol: a client-server method of requesting and delivering HTML web pages
  • HTTPS
    Hypertext transfer protocol secure: encryption and authentication for requesting and delivering HTML web pages, used when sensitive information needs to be transferred e.g. passwords and bank account details
  • FTP
    File transfer protocol: used for sending files between computers usually on a WAN
  • POP
    Post office protocol: retrieves emails from a mail server. Remove it from server and transfers to your device
  • SMTP
    Simple mail transfer protocol: sends emails to an email server