What is Internet made up of?

If we happen to be task oriented and think of a distributed application, then the whole idea from the beginning has been to make distinct differentiation between processing and communication jobs involved in the task. Processing is the job of the host computer (and this computer could be both the client and the server) and communication is the job for network infrastructures and the Internet.

Internet is an open source system. An open source is one, the architecture, design and implementation of which is not proprietary (everyone can get to the source code). That is these details are made public and are accessible to all. The idea is very high interoperability. If a developer of a system wishes for that system to readily connect to a particular system then this is possible if particulars of that system is not proprietary and is accessible to him, that is if that system is open source.

Collaboration is also another underlying idea of open systems or open source. The idea is for the community to collaborate to provide for better, faster, cheaper (mostly free) and more reliable products that are accessible to all. When IT people have access to the source code and they can modify and redistribute it, it evolves.

Internet is open source. What other open systems can you name?

Even the regulating body that regulates the Internet is open. The Internet Engineering Task Force (IETF) is an open international community of technicians, designers, vendors, researchers and operators that are concerned with the operation and development of Internet and Internet technologies. This organisation is open in that any interested individual can join but there is no membership. IETF is not a corporation and is merely a collection of seminars, meetings, and presentations.

Internet could be described as the largest possible Wide Area Network. It is the interconnection between all the Local Area Networks that connect to the Internet. It is the largest sharing of resources and services in the world and it is these resources and services that are the main focus and interest of Internet and not so much the infrastructure that enables the delivery of them. Another words delivery and architecture of this infrastructure is well hidden from the user and all the user cares for is the interesting bits, that is the information he asked for.

Just like any other network, Internet could be conceptualised according to OSI model of communication. There are however a number of protocols within the OSI stack that are predominantly designed for greater interoperability and provision of easier connectivity. What this basically means is that adhering to these standards is crucial for readily connecting to the Internet and being an integral part of it. In particular TCP/IP suite of protocols are the most important. These are in fact two sets of protocols. Transmission Control Protocol (TCP) is a transmission layer protocol and Internet Protocol (IP) is a network layer protocol.

What are the similarities and differences of LAN/WAN based networks and Internet?

The are many (1000s) regional ISPs. These provide individuals and also companies access to the Internet. Examples of regional ISPs could be Freeserve, and AOL. There are also those service providers, referred to as Backbone ISPs. These are not great in numbers and amount to dozens and they operate the high speed networks. The regional ISPs have access to the Internet through the BISPs. The BISPs also provide companies with access to the Internet. Examples of BISPs are At&T, PSINet, and Cable and Wireless. Many regional and backbone ISPs interconnect and exchange information at Network Access Points (NAPs). So Internet is a network of the NAPs, BISPs, ISPs, and on the periphery we have the company networks and the individual users and personal servers. These are the entities on the periphery that are the interesting parts of Internet as they hold the required information and services.

To hosting services that provide access to the electronic information such as books, video, sound, financial markets, .....

Business

use

Home use

Modem Ethernet

LAN

Services

(Email, DNS, Web,..)

Satellite Power lines Wireless Cable TV lines

NAP: Network Access Point

ISP: Internet Service Provider

BISP: Backbone ISP

ISP

Typically an individual, wishing to connect to the Internet from home through a personal computer would need a modem, a telephone line connection and an account with his regional ISP. These regional ISPs also provide their clients with value-added services such as Email, and Web space. A company LAN could connect to the Internet via a regional or a backbone service provider. Access to the internet and to the company resources are through a web server and a security provision such as a Firewall. Corporate needs such as web-hosting and Email services could also be outsourced from these ISPs. Organisations that have a high number of users on a LAN would need a dedicated connection. ISPs could arrange a T1 connection, for which a flat rate is usually charged. The dedicated line is arranged by the ISP through the local telephone company. These ISPs are usually those with significant backbone capacity and those have a direct connection to NAPs are preferred. Each computer that is connected to the Internet is allocated a unique address referred to as its IP address and usually a domain name is mapped onto this IP address. It is through the IP address that computers manage to locate the required resources.