| What is a Network ? |
What is a network ?A computer network is two or more computers linked in some way so that they can communicate. Networked computers can be of any type, such as PCs running Windows or Linux, or Macs, running MacOS, or mainframes running Unix - this does not affect their communication potential, because all speak the same language when talking on a network. A network can be small, with two or three computers in one building; or medium, with a thousand computers connected via an intranet or extranet; or large, with many thousands of computers on a large corporate or government network. Or vast and effectively unmeasurable, as in the case of the Internet, a global free access network.How to build a network ?A simple home or office network could have two computers and an Internet connection. A local network like this is called a LAN. The simplest form of that arrangement would be a cabled network, using a router. The router is the box that connects to the broadband phone network, and has each computer connected to it by cables. The router is the central component and manages the network. The computers need a NIC or network interface card, aka a LAN card. This is often built in now, and is called an 'onboard LAN'.The cables can be replaced by a wireless connection, and this is called a WiFi or wireless LAN. The router then needs a radio transceiver built in, and is called a wifi router. Each computer will need a transmitter / receiver (transceiver) as well, and these are usually plug-in cards with a small aerial, called a wifi card. Newer laptops come with these built in - the aerial is a concealed wire around the screen. Networks can be of any size, as more computers are added then switches or hubs are added in intermediate locations. Cabling must be of higher quality as distances grow and more traffic joins the network. Is cable broadband different from phone broadband ?No - they are exactly the same thing, though the cabling and some of the equipment are of different types. Broadband is correctly termed ADSL or DSL, and both phone and cable broadband are DSL. Cable broadband has some different router and wire specifications because of the way the local area network is cabled and managed, but broadband is broadband.The only other difference is that phone broadband has dynamic IPs and cable broadband has sticky IPs. This refers to the fact that every time you reboot your router on phone DSL you will get a new IP. However on cable DSL, the IPs are allocated for a time period, and you only get a new IP on reboot if the time has expired - these are 'sticky IPs'. In theory cable DSL is better, for two reasons: the actual wire down the street is coaxial not twisted-pair, so the speed and quality potential (ie bandwidth) is much higher; and the contention ratio is better because all subscribers must be permanently connected. A standard (phone line) router cannot be used with cable broadband, as the cable comes in from the street as coaxial wire, which cannot be connected to a normal router. In addition the cable company supply the modem, as they wish to control access to the network. Therefore, unlike normal broadband which uses a modem router to connect, cable broadband needs a router only, which connects to the cable company's modem. If you change from phone broadband to cable broadband, or vice-versa, you have to buy a new router, there is no way to use or modify the other type. What is the Contention Ratio ?This is the ratio of subscribers to the modems, or in practice to the available bandwidth. There are many more subscribers - people paying for the service - than there are facilities to actually service them. Although this seems, on the surface, like fraud perhaps, it is the standard way of providing Internet connectivity to home and normal office users. It works because in practice only a percentage of users will be online. The ratio of users to the equipment necessary to actually allow them to use the Net is the contention ratio. It may be high on cheaper services, around 50 to 1, written sometimes as 50:1. A better service offers 20:1.The two most important factors in choosing broadband are the monthly bandwidth and the contention ratio. Business broadband of the SDSL type offers a much better contention ratio, but is more expensive. Cable broadband has a better contention ratio because more users are connected permanently. Because each is wired to directly from the service provider, a slightly less mobile IP can be ascribed to each user, called a sticky IP. Dial-up phoneline modem users have the worst contention ratios of all, and therefore get the worst service in all respects. Many rural areas still only offer this service. What is the Internet ?The Internet is the largest existing network, and may be regarded as a network of networks. It has millions of computers connected, and no one knows the exact figure - which fluctuates from day to day in any case. A recent estimate is 1.5 billion computers.The Internet consists of all connected computers, a proportion of which are servers with a probable average of about 500 websites each. There are hundreds of millions of sites and at some stage there will be one billion. There are said to be more than 20 billion web pages available, but the real total may be much higher due to the 'invisible web' - pages and other resources that have not been found yet by search engines. The Net has many advantages and disadvantages. For example, it facilitates the distribution of information on an unprecedented scale. It enables global trade on a previously-inconceivable level. But it also allows transgressors and even attackers to operate freely because of its vast size and the way that regions with no effective rule of law can connect. Who invented the Internet ?Nobody
invented the Net, it grew from various origins and combined into
today's vast network. The main people and organisations involved were
Licklider and Roberts at ARPANET, Vint Cerf at Stanford, and Tim
Berners-Lee at CERN. The Net started in crude form in 1969 with the
early form of ARPANET - was improved (and named the Internet) by the
Stanford team in 1974 - much work was done in the intermediate years by
people such as Mills and Jennings at NSF - and had the modern web layer
added by the CERN invention of the HTTP protocol and browser much later
in 1991. A precise answer to this question would probably be that Licklider and Roberts invented the Net, Vint Cerf improved it and named it, and Berners-Lee invented the web - though many thousands have contributed in no small way. A simplified explanation is that the Net is the global connection system, the web is the website and browser system - but it is impossible to separate those two components now. Surely Berners-Lee invented the Net ?We should beware of accepting media opinion as fact. The Net existed for 22 years before Berners-Lee's invention of the web component. Of course, without that, we would have no websites or browsers, so it is perfectly true to say that his contribution was not only critical but irreplacable. However you could probably say the same thing about Robert's and Cerf's work, and Cerf did name the Internet, after all - 17 years before the web was added to it. Berners-Lee invented the worldwide web.Did you like our concise, accurate and efficient description of the Internet? |