Ring topology is a network topology where each computer connected to the circle.With the sense that every computer that is connected into a network of inter-connected to two other computers to form a network similar to the shape of a ring.
The advantages of this topology is the cable that is used can be more conserved.But the shortcomings of this topology is the development of the network will be difficult because each computer will be connected to each other.
This topology is that the initial topology used to connect computers.In this topology each computer will be connected to a cable length with several terminals, and at the end of Kable must end with a terminator.This topology is very rarely used in building a network of ordinary computers because it has several shortcomings including the possibility of its collision data stream, if one device is broken or there is damage to one part of the computer network will not function immediately before the damage is overcome.
This topology is initially used as a medium of instruction Coaxial Kable data and information.But at this point in building this topology in computer network using fiber optic cabal (fiber optic) but combined with other network topology to maximize performance.
Topology refers to the shape of a network, or the network's layout. How different nodes in a network are connected to each other and how they communicate are determined by the network's topology. Topologies are either physical or logical. Below are diagrams of the five most common network topologies.Network topology is a section that describes the relationship between computers are built based on usability, resource constraints and cost limitations, meaning that network topologies can be tailored to the circumstances existing in the field. Network topology there are several forms as follows; Bus topology, Ring topology, Star topology, Tree topology, and Mesh Topology.
An extranet is a computer network that allows controlled access from the outside, for specific business or educational purposes. An extranet can be viewed as an extension of a company's intranet that is extended to users outside the company, usually partners, vendors, and suppliers. It has also been described as a "state of mind" in which the Internet is perceived as a way to do business with a selected set of other companies (business-to-business, B2B), in isolation from all other Internet users. In contrast, business-to-consumer (B2C) models involve known servers of one or more companies, communicating with previously unknown consumer users. An extranet is like a DMZ in that it provides access to needed services for channel partners, without granting access to an organization's entire network.
Extranet atau Ekstranet adalah jaringan pribadi yang menggunakan protokolinternet dan sistem telekomunikasi publik untuk membagi sebagian informasi bisnis atau operasi secara aman kepada penyalur (supplier), penjual (vendor), mitra (partner), pelanggan dan lain-lain
Baik internet dan intranet menggunakan protokol yang sama untuk transfer data. Pada dasarnya hal besar yang membedakan mereka adalah bahwa intranet adalah sebuah jaringan local dari komputer sedangkan internet adalah massa terhubung beragam komputer. Sebuah perusahaan akan memiliki intranet yang lokal kepada mereka.
Both the internet and an intranet use similar protocols for transfer of data. Basically the big thing that sets them apart is that an intranet is a localized network of computers whereas the internet is a diverse connected mass of computers. A company will have an intranet that is local to them.
Source: http://wiki.answers.com/Q/What_are_the_similarities_between_the_intranet_and_the_internet
