Protocols

Protocols



Protocols are the formatting rules that specify how data is changed into messages. Transmission control protocol (TCP) and Internet Protocol (IP) manage the flow of information in the Internet together. Transmission control protocols manage the assembly and reassembly of information and data from one computer to another. Internet protocol manages the transfer of data between computers. There are different types of protocol including:

• HyperText Transfer protocol- controlling the requesting and transferring of HTML web pages across the Internet
• File transfer protocol - controls the sending of information and files from one computer to another.
• Post office protocol 3- controls the transfer of emails between computer systems
• Secure sockets layers- a cryptographic system for sending data like credit card details over the Internet.

Standards

De Facto Standards

A de facto standard is when no formal agreement is in place. This means that a verbal agreement between manufacturers is being followed. De facto standards tend to be widely used however they are not recognised by a standards agency.
De facto standards tend to be used in the hardware, software industry as well as protocol and formats. Manufactures and producers tend to follow a common layout and standard however the standards agencies are not aware of it.

GIF format for pictures is an example of de facto standards, the standards agencies have not enforced that format however it is widely used by web developers.


De Jure Standards

De jure standards are legally binding standards which are approved by a standards agency and must be followed by every manufacturer. These standards places restrictions on manufactures which some people feel slows development however it minimises any compatibility issues people have.

Wi-Fi, the wireless network is part of a de jure standard. The standards agency has made it so that all of the wireless networks have to be the same.

The Internet and The World Wide Web

The Internet

The Internet is a large group of interconnected computers which span across the world. It allows information to be sent and receive from one computer to another. The Internet was originally developed by Advanced Research Projects Agency so that universities could access research carried out by other universities.

The World Wide Web

This is a collection of multimedia resources which can be found on the internet. Web browser software is used to access these files through the use of HyperText Transfer Protocol (HTTP). Webpages are usually written in HyperText Markup Language (HTML) and the different pages are linked together using hyperlinks.

Network designs

Peer-to-peer networks


A computer network in the simplest of terms is two computers which are linked together. Each computer needs a network interface card and the connection is made either by using crossover cables or by using wireless. An operating system can be used to define which resources are shared and the basic network in place. If the network has more than two computer is in a hub could be used to provide the connectivity. All of the computers have similar rights. This type of network does not need a dedicated operating system. Wireless connections are now more common which means a wireless router is needed.

Advantages of a peer-to-peer network:

• the cost is generally low due to the ability to share peripherals.


• information can be shared freely between computers and employees.

Disadvantages of a peer-to-peer network:

• there is not main computer or database which means changes and administrative things are more complicated, as well as affecting the ability to back-up files successfully.


• the computers are link which means that if a virus affects one computer it is more likely that it would spread to other computers.
  

Client-server networks

A server is a powerful machine which forms the entire basis of a network. The server needs a specialised network operating system which can cope withe the complex set of user rights and file permissions. Servers are usually fitted with RAID drive systems to ensure that the data remains available to the network if the drive files or data become corrupted. The server is connected to network switches. Switches are located nearly the same as hubs because they are pieces of hardware that joins multiple computers together. Client-server networks are networks which are connected using a server. This means that there is one central server which can be backed-up and can restrict the viewing of files.

Advantages of client-server networks:

• the system can be easily backed-up and managed from a central computer.
• it is easier to control the security of the system and the maintenance of the system
• it is generally very cheap to replace a workstation.

Disadvantages of a client-server networks:

• the server needs to be very powerful. If it is not the system will not run which means that the comapny will have to pay for the correct server.

Homework - 3

Give an example of where a peer-to-peer network is used and list the disadvantages of using this network.

Homework - 2

Explain how a Client-server network connects the computers together and list the advantages of doing this.

Homework- 1

Explain the advantages and disadvantages of using an Intranet in a company.

Intranets and Extranets

What is an Intranet?

An Intranet is a private computer network which uses Internet protocols and network connections to securely share any part of an organisation's information or operational systems with its employees.

Advantages of an Intranet:

• Workforce productivity can increase due to the fact that users locate and view information faster.
• Time taken to do work will decrease because employees have the ability link to relevant information at a time which suits them.
• Communication will improve because the company is able to have a world wide range when communicating with other offices in the company.
• It will save money because users can view information and data via web-browser rather than maintaining physical paper based documents.

Disadvantages of an Intranet:

• It is an evolving technology that requires upgrades and could have software incompatibility problems
• Some employees may not have computers at their desk
• Maintaining the content can be time consuming
• Security features can be inadequate
• Inadequate system performance management and poor user support

What is an Extranet?

An extranet is a private network that uses Internet technology and telecommunication networks to securely share a business's information with suppliers, partners, or customers. An extranet can be viewed as part of a company's intranet that is extended to users outside the company.

Advantages of an Extranet:

• Extranets can improve organization productivity by automating processes that were previously done manually
• Extranets allow organization or project information to be viewed at times convenient for business partners, customers, employees, suppliers and other stake-holders.
• Information on an extranet can be updated, edited and changed instantly.
• Extranets can improve relationships with key customers, providing them with accurate and updated information.
  

Disadvantages of an Extranet:

• Extranets can be expensive to implement and maintain.
• Security of extranets is a big concern when dealing with valuable information.
• Extranets can reduce personal contact with customers and business partners.

Types of Networks

WAN - Wide Area Network

This covers a large geographical area and connect computers and LAN’s with the use of cables, satellites and a modulator demodulator. WAN’s allow computers to communicate between each other even if there is a large geographical gap. The largest and most popular example of a WAN is the Internet. The Internet is used by most computer literate people.

Advantages of a WAN

• Allows computers to communicate between each other regardless of the physical location of the computer.
• Allows information to be shared between a large number of people.

Disadvantages of a WAN

• Viruses can be spread through a computer system because all of the computers are linked.
• Hackers are a problem with networked computers because they all contain information which could be useful.
• Managing a large system takes high abilities which means that someone would need to be employed/trained.

LAN - Local Area Network

This covers a small geographical location, usually just a site. This network is linked through a series of cables. LAN's are most commonly used in buildings and offices. They allows users on the system to share data with anyone else on the network. A file server is used to store all of the information on a LAN network.

Advantages of a LAN

• Users are able to share peripherals & resources (saving money).
• Security is good within the network unlike the risks associated with WAN’s.
• Files can easily be shared between users.
• The file server can easily be backed up to protect the data.

Disadvantages of a LAN

• File servers and network cabling can be quite expensive.
• The network has to managed very effectively, especially considering LAN’s in schools or office buildings.
• Viruses can easily be spread throughout other computers within the network.
• If the file server crashes or is hacked, the whole network is at risk.

MAN - Metropolitan Area Network

This covers an area such a city, town or campus. This network could be connected through cables, microwaves and satellites. This network falls in the geographical grey area between a WAN and a LAN. It can connect small LANs to large WANs

What is an ICT network?

What is an ICT network?

Networks are made up of thousands of computer devices connected by different types of transmission media such as telephone lines, satellites, and fiber optics. Computer networking is the linking of two or more computing devices together for the purpose of sharing data , software and peripherals.

Why use a networked system rather than a standalone?

Networking computers together can increase the efficiency and effectiveness of the work being done within the system. Using a network allows the business and users of the system to share resources. They can share software and peripherals with the other computers which means that money can be saved because the number of software and peripherals needed is less as well as time because there is no need to move to another computer to, for example, print a document.