THE PHYSICAL STRUCTURE AND STANDARDS OF THE INTERNET (STUDY OBJECTIVE 3)

THE NETWORK

Exhibit 14-3 shows the types of organizations that make up the interconnected networks of the Internet. The Internet includes backbone providers, network access points, regional Internet service providers (ISPs), local ISPs, and Internet subscribers. The Internet is a hierarchical arrangement: There are a few large backbone providers, many more regional and local ISPs, and millions of Internet subscribers. Internet subscribers are the individual users of the Internet.

A backbone provider is an organization which supplies access to high-speed transmission lines that make up the main network lines of the Internet. Much like the way that your spinal bones, or backbone, support all the skeletal systems of your body, the Internet backbone is the main trunk line of the Internet. The backbone has extremely high capacity and high-speed network lines. The actual speed and capacity of the backbone lines continually increase as the technology is upgraded, and the speed of the U.S. backbone is 1 trillion bytes per second. This means that one trillion bits of data could be transmitted over the network lines in one second. The backbone providers connect to each other either directly through private lines or through network access points (NAPs). Major backbone providers in the United States are companies such as Sprint, AT&T, and UUNET.

Regional ISPs connect to the backbone through lines that have less speed and capacity than the backbone. The network lines used to connect regional ISPs to the backbone are usually T3 lines. A T3 line carries data at 44.476 megabits per second (44 million bits per second). Local ISPs connect to regional ISPs by either T3 or T1 lines. A T1 line carries data at a speed of 1.544 megabits per second (Mbps). Regional and local ISPs usually use several T3 or T1 lines simultaneously. You might envision how this works by thinking about water hoses. If you squirt one water hose at a house fire, only a small volume of water reaches the fire. The use of four water hoses, all aimed at the same fire, will send four times the volume of water. Examples of local ISPs are local telephone companies and local cable companies.

Exhibit 14-3 Architecture of the Internet

Local ISPs connect individual users to the Internet. These Internet subscribers are connected to local ISPs using either dial-up modems, digital subscriber lines (DSL), or cable TV lines. Dial-up modem speeds are typically 56 kilobytes per second, while DSL speed is usually approximately 5 mbps and cable broadband speeds are approximately 5 to 10 mbps.

At each of these organizations and gateways, there are computers that function as Web servers. A Web server is a computer and hard drive space that stores Web pages and data. These Web servers respond to requests for Web pages or data, and transmit the Web pages or data over the network. Through these interconnected networks and Web servers, any computer connected to the Internet can communicate with any other computer on the Internet. This system enables e-business, e-commerce, and e-mail to function as we know it today.

THE COMMON STANDARDS OF THE INTERNET

Since any computer can theoretically link to any other computer on the Internet, there must be common and standard methods to display and communicate the data transmitted via the Internet. Each computer on the Internet uses the TCP/IP protocol to communicate with the network. While every computer connected to the Internet could possibly be part of the World Wide Web, every such computer is not necessarily part of the Web. The World Wide Web is an information-sharing network that uses the Internet as the network to share data.

Web pages that are part of the World Wide Web are available to anyone using a Web browser. However, a common way to present and read the data on a Web page is also necessary. The language invented to present data on websites is HTML, a hypertext markup language. Nearly all websites use HTML to format the words, data, and pictures that you see on a Web page. Exhibit 14-4 shows a very simple Web page and the HTML source code that formats and presents the words and the arrow symbol on this Web page. There are many users of the Internet throughout the world, using different types of computers with different operating systems. The common formatting language HTML for Web pages allows any computer to display the Web page the way it was intended to be displayed. HTML has evolved over the years to increase functionality and security. The current standard, HTML 5, allows much richer use of video and audio, as well as better security than the previous versions. These enhancements make the Internet user-friendly for browsing, and also increase its usefulness for e-commerce or e-business.

In addition to a standard communication protocol and a standard formatting language for Web pages, there must also be a common addressing method to store and locate Web pages. The addresses of websites and Web pages use a uniform resource locater (URL) address. A URL is the address you type in to reach a website. For example, the URL address of the Google search engine is http://www.google.com. The “http” in a URL address stands for “hypertext transmission protocol.” When you type in a URL, your Web browser actually sends an http command to a Web server, directing the server to find and transmit the Web page you requested.

In a URL address such as http://www.google.com, the google.com part is called the domain name—the unique name that identifies the Internet site. Organizations must register a domain name to own its exclusive use. For example, The Coca-Cola Company has registered, and pays a monthly fee to own and use, the domain name coke.com. Domains have a suffix that indicates the type of organization owning the rights to that domain name. In the United States, some of the common suffix portions of domain names are as follows:

For domains outside the United States, the suffix indicates the country. For example, .ca is Canada and .au is Australia.

The URL addressing system actually uses IP addresses rather than domain names that are spelled out. An IP address is an Internet protocol address. A given domain name is associated with a single IP address. In the same way that your postal address allows your mail carrier to locate your exact home, an IP address is the unique information that allows a specific website or server to be located.

There are specialized servers on the Internet called domain name servers (DNS), which function to store, index, and provide the IP address for each domain name. When a domain name such as coke.com is typed into a Web browser, a request is sent to a DNS to find the IP address of the domain, and the website is located on the basis of the IP address.

Exhibit 14-4 A Simple Web Page and the HTML Source Code.

Since the Internet is an open network system that anyone can access, there are those who misuse the Internet for illegal and fraudulent activity. Examples of such risks are hackers, identity thieves, password sniffers, and denial of service attacks. Without an extra layer of protection, any data exchange between a user and a Web server is open for anyone to read. This means if you enter your credit card number on an e-commerce website, your credit card number and other data can possibly be intercepted. Therefore, the majority of e-commerce sites use common forms of encryption and data protection.

The standard form of encryption embedded in e-commerce sites and in Web browser software is secure sockets layering (SSL), an encryption system in which the Web server and the user's browser exchange data in encrypted form. The Web server uses a public encryption key, and only the browser interacting with that Web server can decode the data. Web browsers in use today use 128-bit encryption. Persons using a Web browser will know they are connected to a secure encrypted site that uses SSL by seeing two things in their Web browser. First, a website using SSL will have a URL address that begins with https://. The extra “s” at the end of the http denotes a secure site. Also, most browsers show a picture of a locked padlock in the lower bar of the Web browser. SSL and encryption allow the general public to conduct e-commerce over websites with less fear of exposure regarding credit card or other private information.

The Internet network, the World Wide Web, and the common standards used allow the general public to browse the Web, share data, send e-mail, and conduct e-commerce. The next section describes e-commerce.