Networks

Networks

1. Factors to consider when choosing a network

   • Cost of the network
     • Initial purchasing of equpitment
     • Installation and Training
     • Maintenance costs
     • Size of the available budget will determine what can be done
   • Size of the organisation
     • The needs can range from small LAN's to a global WAN
     • Some communications media are limited to the distance they have to travel
     • The amount of data that will be processed should also be considered
   • How the system will be used
     • What type of applications do users require
     • Will they need large data storage
     • From where will they operate the network(At home, in office or remote access from different locations
   • Existing system to integrate
     • Often networks are not developed from scratch but need to fit in the with existing systems.
       • Sometimes an extension is required to an organisation (When a new branch office opens)
       • So any new network must fit in with the operating systems and protocols of the existing
     • It must support any peripherals already in use (Printers)
     • can current stock of PC's and peripherals be used on the new network
   • Performance and speed required
     • For performance - Reliability, user friendliness, capacity and speed of processing
     • Different parts of the organisation may have different performance requirements.
       • In an organisation, a real time E-commerce system may require greater speeds and capacity and security than a in house payroll systeem
   • Security Issues
     • Networks allow users to access the internet and company data needs to be protected and access to the internet might need to be controlled.
     • Access to illicit material (Pornography, sites promoting extremism of any kind)
     • Whether to restrict searches for certain words
     • Protecting payment details when transmitted
     • Restricting staff access to certain files
     • Controlling access to copyright material

2. Types of networks available

   • Client server network
     • Networks that have computers or terminals that are connected to a more powerful computer called the network server
       • Central file server stores the data and programs.
       • A print server would spool data ready for when the printer is ready
       • A communication servers (Web server) may control an email and internet access
     • ADVANTAGES
       • Faster processing of tasks
       • Can manage large networks
       • Security is better as it is centralized and one persons responsibility
       • offers easy access to centralized data
     • DISADVANTAGES
       • More expensive as software system more complex and need to buy server.
       • Is server crashes or cable fails no user can continue work
       • Require specialist personnel to manage system
   • Peer to peer network
     • All stations are joined together in the network have equal status and each station can communicate directly with every other work station on the network without going through a server
     • ADVANTAGES
       • Easy to set up
       • No reliance on a server
       • Lower operating costs
       • Peer responsibility where users decide what resources others can use on their computer
     • DISADVANTAGES
       • Slower processing of tasks
       • Only works well on small networks
       • Security and backup are not centralized and difficult to manage
       • Access to data depends upon the owner's permission
       • Harder to find files which are not stored centrall

3. TOPOLOGIES

   • BUS
     • Workstations are connected to the main central cable where data can travel in both directions
     • ADVANTAGES
       • Less cable needed than a ring, so its relatively cheaper and easier to install and maintian
       • Easy to add new nodes by removing erminator
       • If a work station/workstation goes down the other terminals will continue
     • DISADVANTAGES
       • Heavy traffic can cause network failure and delays
       • Heavily dependent upon the cable backbone and cable damage can cause network failure
   • RING
     • ADVANTAGES
       • No dependence upon a central host
       • Very high transmission speeds are possible
       • Routing between devices is simple because messages normally travel in one direction.
       • No collisions
       • Cabling costs less than other topologies
       • Each computer has the same access as others so no one node can dominate the network
     • DISADVANTAGES