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Chapter (2) Network Fundamental and Layered Network Architecture

Figure 2-4 shown a SAN Hierarchy

https://www.youtube.com/watch?v=fOTvN3ZzbOM

2.4.4.2 Intranets and Extranets

One common configuration of a LAN is an intranet. Intranet web servers differ from
public web servers in that the public does not have access to an organization’s intranet without
the proper permissions and passwords. Intranets are designed to be accessed by users who have
access privileges to an organization’s internal LAN. Within an intranet, web servers are installed
in the network, and browser technology is used as the common front end to access information
such as financial data or graphical, text-based data stored on those servers.
An extranet is an intranet that is partially accessible to authorized outsiders. Whereas an
intranet resides behind a firewall and is accessible only to people who are members of the same
company or organization, an extranet provides various levels of accessibility to outsiders. You
can access an extranet only if you have a valid username and password, and your identity
determines which parts of the extranet you can view. Extranets help extend the reach of
applications and services that are intranet-based but that employ extended, secure access to
external users or enterprises. This access is usually accomplished through passwords, user IDs,
and other application-level security. Therefore, an extranet is the extension of two or more
intranet strategies with a secure interaction between participant enterprises and their
respective intranets. The extranet maintains control of access to the intranets within each
enterprise in the deployment.
Extranets link customers, suppliers, partners, or communities of interest to a corporate
intranet over a shared infrastructure using dedicated connections, as shown in Figure 2-5.

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