Internet. Network hierarchy

The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite (TCP/IP) to serve several billion users worldwide. It is a network of networks. With hierarchy, all computers on the internet are connected. A hierarchy is an organizational structure in which items are ranked according to levels of importance. Internet is such a huge network of several different interlinked networks relating to the business, government, academic, and even smaller domestic networks, therefore internet is known as the network of all the other networks. These networks enable the internet to be used for various important functions which include the several means of communications like the file transfer, the online chat and even the sharing of the documents and web sites on the WWW, or the World Wide Web.

A hierarchical network is the type of network topology in which a central "root" node (the top level of the hierarchy) is connected to one or more other nodes that are one level lower in the hierarchy (i.e., the second level) with a point-to-point link between each of the second level nodes and the top level central "root" node, while each of the second level nodes that are connected to the top level central "root" node will also have one or more other nodes that are one level lower in the hierarchy (i.e., the third level) connected to it, also with apoint-to-point link, the top level central "root" node being the only node that has no other node above it in the hierarchy.

The Internet contains billions of web pages created by people and companies from around the world, making it a limitless location to locate information and entertainment. The Internet also has thousands of services that help make life more convenient. A network structure is more a star topology whereas a Hierarchical structure is like a tress...

Every computer that is connected to the Internet is part of a network, even the one in your home. For example, you may use amodem and dial a local number to connect to anInternet Service Provider(ISP). At work, you may be part of a local area network (LAN), but you most likely still connect to the Internet using an ISP that your company has contracted with. When you connect to your ISP, you become part of their network. The ISP may then connect to a larger network and become part of their network. The Internet is simply a network of networks.

Most large communications companies have their own dedicated backbones connecting various regions. In each region, the company has a Point of Presence (POP). The POP is a place for local users to access the company's network, often through a local phone number or dedicated line. The amazing thing here is that there is no overall controlling network. Instead, there are several high-level networks connecting to each other through Network Access Points or NAPs.

37) Concept ISP

Stands for "Internet Service Provider." In order to connect to the Internet, you need an ISP. It is the company that you (or your parents) pay a monthly fee to in order to use the Internet. If you use a dial-up modem to connect to your ISP, a point-to-point protocol (PPP) connection is established with another modem on the ISP's end. That modem connects to one of the ISP's routers, which routes you to the Internet "backbone." From there, you can access information from anywhere around the world. DSL and cable modems work the same way, except after you connect the first time, you are always connected. An Internet service provider (ISP, also called Internet access provider) is a business or organization that offers users access to the Internet and related services. Many but not all ISPs are telephone companies or other telecommunication providers. They provide services such asInternet access, Internet transit, domain name registration and hosting, dial-up access, leased lineaccess and colocation. Internet service providers may be organized in various forms, such as commercial, community-owned, non-profit, or otherwise privately owned.

An ISP is also sometimes referred to as an IAP (Internet access provider). ISP is sometimes used as an abbreviation for independent service provider to distinguish a service provider that is an independent, separate company from a telephone company.

For a monthly fee, the service provider usually provides a software package, username, password and access phone number. Equipped with a modem, you can then log on to the Internet and browse the World Wide Web and USENET, and send and receive e-mail. For broadband access you typically receive the broadband modem hardware or pay a monthly fee for this equipment that is added to your ISP account billing.

In addition to serving individuals, ISPs also serve large companies, providing a direct connection from the company's networks to the Internet. ISPs themselves are connected to one another through Network Access Points (NAPs).

So Many ISPs provide additional services such as e‑mail accounts, web browsers, and space for you to create a website.

38) " Last mile " access

The last mile, in the context of telecommunications, refers to the technology providing connection services to and from the user’s office or house. In last mile technology, signals are carried via any kind of digital medium from the broad telecommunication backbone toward the comparatively short distance to and from the user’s home or business. Last mile technology is the final connectivity leg between the telecommunication service provider and an individual customer. Note that the term is figurative -- the actual distance can be more than a mile, particularly in rural areas. In distant and rural areas, it is a challenge for telecommunication service providers to offer high-tech, high speed and high bandwidth services to every single subscriber because of the high cost of using fiber optic cables or wires, as well as maintenance expenses.

The “last mile” is the copper or fiber feeder wire – also known as the “local loop” – that goes directly into individual homes or businesses.

Last-mile technology is any telecommunications technology that carries signals from the broad telecommunication backbone along the relatively short distance (hence, the "last mile") to and from the home or business. Or to put it another way: the infrastructure at the neighborhood level.

In many communities, last-mile technology represents a major remaining challenge because the cost of providing high-speed, high-bandwidth services to individual subscribers in remote areas can be higher than the service provider would like. Laying wire and fiber optic cables is an expensive undertaking that can be environmentally demanding and require high maintenance. Experts hope that broadband wireless networks will eventually provide the solution and meet everyone's needs. Today, last-mile technologies include:

· plain old telephone systems (POTS)

· ISDN, a somewhat faster technology than regular phone service

· Digital Subscriber Line (DSL) over existing telephone twisted pair lines

· cable and the cable modem for data, using the same installed coaxial cable that already is used for television

· wireless, including satellite services such as DirectTV

· optical fiber and its transmission technologies