Network characteristics and uses
Networks are collections of connected devices such as traditional desktop and laptop computers, mobile devices and shared peripherals such as printers and storage devices.
Networks operate with local areas as well as on a global scale therefore it is vital that any devices connected to the network are all able to communicate with each other.
LAN and WAN
Client-server V Peer to Peer
Client server characteristics
- Devices on networks are either clients or servers
- Used in medium to large organizations
- At least one server e.g. File, printer, back-up, application
- Clients are devices (e.g. computers)
- Clients log on to the network
Username/ swipe card and password or fingerprint then they have access to:
-Private storage space, printers, files, software, internet.
Client server disadvantages
- Requires technical expertise
- If server fails, clients can not operate
- Operations can be managed centrally
- Back-ups
- Software deployment
- Anti-virus update
- Users can log on using any client
- More processing power available at client
- Security is structured centrally
- Servers are powerful and can be very expensive
- Lots of network traffic
Peer to peer characteristics
- No central server
- Computer perform own functions
- Computers can share each others resources (ex Printers, Files, Scanner, Internet connection)
Peer to peer implications
- Easier to manage on a small scale
- Can be set up in homes/small businesses
- All computers need to be maintained individually
- Backups need to be made at each computer
- Anti-virus software must be kept up to date
- Users need to use same computer each time
- Security issues
- Software needs installing on each computer
- No reliance on a single server
- Less network traffic than client-server
Protocol
Devices on a network must be able to talk to each other.
Protocol is a set of rules which define:
- How to establish communication between machines (wired/wireless/serial/parallel)
- The format of data which is exchanged
- How errors in the data are to be detected
- How errors are corrected
- Methods of compression (faster and more efficient)
- How the connection is to be terminated
- Rate at which data is sent and received by devices (bit rate)
FTP – File Transfer Protocol (SFTP) Application
HTTP – Hypertext Transfer Protocol (HTTPS) Application
POP3 – Post Office Protocol Application
SMTP – Simple Mail Transfer Protocol Application
TCP – Transmission Control Protocol Transport
IP – Internet Protocol Network
MAC – Medium Access Control Data link
USB – Universal Serial Bus Physical
Network layering
Layering (splitting tasks/protocols up) is an important concept in networking.
Not only does it make it easier to understand what makes up a protocol (adding a level of abstraction) and a valid connection but it also has the primary advantage of allowing changes to each layer to be made without affecting the others:
This means manufacturers can produce devices for a given layer knowing that they will be compatible with other devices of that layer & only one layer of a protocol needs altered without having to change the whole protocol (IPv4 —> IPv6)
A good example would be building a desktop PC, the protocols and software which allow the devices to communicate also allow easy upgrades and interoperability.
Example: http://store.virginmedia.com/discover/broadband/ultrafast.html
Compsci 8
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