Networks 1

Networks 1

1. Types of Networks

   • Local Area Networks
     • Small geographical area. On a single site
     • Hardware for it is owned by the organisation
     • Wired or wireless
     • Found in businesses, schools and universities
     • Can connect to various devices
     • Why Use LAN
       • Sharing files is easier
         • Network users can access the same files, work collaboratively and copy files between machines
       • Share the same hardware e.g. a printer
       • Internet connection can be shared between every device
       • Install and update softwares on all computers at once
       • Communicate with LAN users cheaply and easily
       • User accounts can be stored centrally, so users can log in from any device
   • Wide Area Networks
     • A network that connects LANs
     • Connects LANs that are in different geographical locations
       • Example: A business with offices in three different countries would need a WAN for all their devices to connect together
     • Organisations hire infrastructure e.g. communication lines for telecommunications companies, who own and manage the WAN.
     • More expensive then LAN
     • May be connected using fibre or copper telephone lines, satellite links or radio links
     • The Internet is the biggest WAN

2. Factors that affect the performance of Networks

   • Bandwidth is the amount of data that can be transferred in a given time
     • The greater the bandwidth, the better the network can perform
     • Available bandwidth is shared between users of a network - too many users or heavy-use may cause congestion and slow the network
     • You can limit the bandwidth available to individual users
   • Choice of hardware other than cables and network topology
   • Wired connections are generally faster and more reliable than wireless
     • Fibre optic cables can give much better performance than copper cables
   • Wireless performances depends on signal quality so is affected by the range of the device, the amount of interference from other devices and physical obstructions like thick walls in buildings

3. The different roles of computers in a client-server and a peer-to-peer network

   • Client-Server Networks
     • Is managed by the server. The devices connected to the server are clients
     • Files and software are usually stored centrally on the server rather than on individual client devices
     • Clients send requests to the server e.g. asking for data
       • The server processes the request and responds
         • This is the client-server relationship
     • The server stores user profiles, passwords and access information - it may request a password before fulfilling certain requests or deny requests to users without the right access level
     • Most uses of the Internet work on a client-server relationship
     • Pros
       • Easier to keep track of files as they're stored centrally
         • Easier to perform back-ups
           • Easier to install and update software
             • Easier to manage network security e.g. anti-malware software and user access levels
               • Servers are very reliable and are always on
     • Cons
       • Expensive to set up and needs IT specialists to maintain the network and server
         • Sever dependence - if the server goes down all clients lose access to their works
           • The server may become overloaded if too many clients are accessing it at once
   • Peer-to-Peer Networks
     • Don't use servers
     • All devices are equal, connecting directly to each other without a server
     • May be used at home
     • Pros
       • Easy to maintain
         • You don't need any expertise or expensive hardware
       • No dependance on server
         • If one device fails the whole network isn't lost
     • Cons
       • No centralised management - devices need their updates and security installed individually. Back ups are also more complicated
         • Copying files between devices creates duplicate files - it's easy to lose track of what's stored where and which files are up-to-date
           • Peer machines are less reliable and data may be lost if one fails
             • Machines are prone to slow-down when other devices access them