Page 22 - Handout Computer Network.

Figure 2-5 shown an Intranets and Extranets Hierarchy

https://www.youtube.com/watch?v=4_zSIXb7tLQ&t=30s
https://www.youtube.com/watch?v=HEzN3B_aXE4&t=26s

2.5 Virtual Private Networks

A virtual private network (VPN) is a private network that is constructed within a public network
infrastructure such as the global Internet. For example, using a VPN, a telecommuter can access the
company headquarters’ network through the Internet by building a secure tunnel between the
telecommuter’s PC and a VPN router in the headquarters. Cisco products support the latest in VPN
technology. A VPN is a service that offers secure, reliable connectivity over a shared public network
infrastructure such as the Internet. VPNs maintain the same security and management policies as a
private network. They are the most cost-effective method of establishing a point-to-point connection
between remote users and an enterprise customer’s network.

Three main types of VPNs exist, as shown in Figure 2-6:

• Access VPNs provide remote access for a mobile worker and small office/home office
(SOHO) to the headquarters’ intranet or extranet over a shared infrastructure. Access
VPNs use analog dialup, ISDN, DSL, mobile IP, and cable technologies to securely
connect mobile users, telecommuters, and branch offices.
• Intranet VPNs link regional and remote offices to the headquarters’ internal network
over a shared infrastructure using dedicated connections. Intranet VPNs differ from
extranet VPNs in that they allow access only to the enterprise customer’s employees.
• Extranet VPNs link business partners to the headquarters’ network over a shared
infrastructure using dedicated connections. Extranet VPNs differ from intranet VPNs
in that they allow access to users outside the enterprise.

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