INTERNETWORKING –

 An internetworking is the process or technique of connecting different types of networks or network segments for making large global network by using routing technology. Internetwork is used in data communication between networks which is owned and operated by different entities using a common data communication and the Internet Routing Protocol.

Two or more networks or network segments connect using devices that operate at layer 3 (Network Layer) of the OSI Basic Reference Model such as a router. Any interconnection among or between commercial, public, private, and industrial or governmental networks may also be defined as an internetwork. It allows people and their computers to communicate across different kinds of networks.

Interconnected networks use the Internet Protocol. There are three variants of internetworks such as Intranet, Extranet and Internet.

1. Intranet – An intranet is a set of networks, using the Internet Protocol and IP-based tools such as web browsers and file transfer applications which are under control of a single administrative entity. The administrative entity closes or contact to all but specific authorized users. In other words, an intranet is the internal network of an organization. A large intranet network will have one web server to provide users with organizational information.
2. Extranet – An extranet is a controlled private network which allows access to vendors, partners, and suppliers or an authorized set of customers. It is a part of intranet in which selected people outside the company can use.
3. Internet – Internet is the largest network in the world. It consists of a worldwide interconnection of academic, governmental, private and public networks which is based upon the networking technologies of the Internet Protocol Suite.