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