Internet Infrastructure - Elements Of The Internet Infrastructure

ELEMENTS OF THE INTERNET INFRASTRUCTURE

At the most rudimentary level of the Internet infrastructure are endless miles of telephone lines and fiber optic cable. These cables connect millions of individual users and businesses to other parties, transmitting data at varying speeds, depending on the types of cabling used. Another factor that affects the speed and quality of a user's connection is the means of connection, which include telephone modems; high-speed connection methods like cable modems, ISDN, DSL, and T1 lines; and company networks. According to the Strategis Group, high-speed residential Internet service was expected to surpass telephone dialup methods in the United States by 2005, at which time Strategis predicted there would be 36 million broadband subscribers.

It's easier to understanding how pieces of the Internet infrastructure work if one visualizes them transmitting data. The first step involved in sending or receiving data involves ISPs, which maintain racks upon racks of modems. Users connect to these modems in order to gain access to the ISP's network, which can vary in reach depending on the ISP's size. In the early 2000s, there were more than 7,000 ISPs throughout the world. The top 10 accounted for only 25 percent of total Internet access traffic. Once connected to an ISP, users then attempt to communicate by sending e-mail messages to other Internet users or by requesting Web pages or downloadable files from any number of servers located across the world. Servers are the computers used by individuals, companies, and other organizations to host Web sites, e-mail systems, or files that can be downloaded.

The process used to send and receive information across the world is more or less hidden to the user, and occurs in just seconds. In order for this to happen, a user on one ISP's network must be able to connect to users on another ISP's network, which may be located across the nation or across the globe. An exception to this would be if two users were located on the same ISP's network. ISPs connect to one another at NAPs, also called Internet exchanges (IX), which are major pieces of the Internet's backbone.

When the NSF opened the Internet to commercial enterprises in 1995, the first NAPs were located in Chicago; Pennsauken, New Jersey; Washington, D.C.; and San Francisco. These were operated by Ameritech, Sprint, Pac Bell, and MFS (a predecessor of MCI WorldCom). MFS later created two coastal access points called metropolitan area exchanges (MAE). By the early 2000s, there were more than 10 major access points throughout the United States. Sometimes ISPs make arrangements to establish direct connections between their networks. Known as private peering, this eliminates the need for relying on one of the major NAPs and helps to reduce congestion on the Internet.

Devices known as routers make sure that the packets of data sent from a computer on one ISP's network are sent to the intended machine on another local or wide-area network via the quickest, most efficient route, in accordance with communication protocols like TCP/IP. Just as the post office needs to know a street address before it can deliver a letter, routers need to know the address of the device to which information is being sent via the Internet. All devices communicating on the Internet, including servers used to host Web sites, have unique Internet Protocol (IP) addresses, which are four sets of numbers separated by decimals. Corresponding to numeric IP addresses are domain names, which are easier for humans to remember than long sequences of numbers. In the Web site address www.yahoo.com, .COM (like .ORG or .NET) is called the top-level domain and the word Yahoo is called the second-level domain. As the Internet evolved, a distributed database called the Domain Name System was created which contains all of the domain names and IP addresses associated with registered entities. Domain name servers located across the Internet are responsible for finding registered domain names and converting them to IP addresses so a connection can occur.