Basics of VPN Unearthed


Basics of VPN Unearthed


There has been a paradigm shift in the approach to corporate networking since the advent of Internet as a business communication medium. Given the ubiquitous nature and low access cost of the internet, other more attractive networking solutions have started arriving in the IT marketplace. Virtual Private Network (VPN) technology has started replacing conventional leased circuit-based WANs. Sometimes collaborative, unified approach is required to exchange information between employees, business partners and selected authorized persons. A VPN is the infrastructure that makes such deployment possible in a cost-effective manner.

What is a VPN?

A VPN is basically a corporate network built around the communication infrastructure of the Internet instead of leased lines or RAS using direct dial-in. A VPN is, however, a highly cost effective proposition as dedicated lines are required only to connect the corporate network to an ISP (Internet Service Provider). Remote users of a VPN also connect to the network through the Internet using local dialup access numbers of the ISP. This offers a very high degree of availability and Quality of Service (QoS) as opposed to long distance dialing. The actual savings will depend on many factors including the geographical spread of enterprise branch locations, the number of remote users, locations from where remote access is generally made and the average time of use by the remote users. It has been reported that a saving of up to 50% is possible by changing over from a conventional WAN to a VPN. Capital expenditure payback periods for VPN implementation can be as low as four months.

Types of VPN

VPN clients and servers are typically used to support remote access to an intranet, support connections between multiple intranets within the same organization, and inter link networks between two organizations, forming an extranet. Based on this VPNs are classified into three distinct types:

    • Inter-site or inter-LAN VPNs: These provide connectivity among multi-user branch office LANs and the central enterprise LAN through the Internet.
    • Remote access VPNs: These provide many-to-few of connectivity for mobile remote users and telecommuters to a corporate LAN through the Internet.
    • Extranets VPNs: These are used to share information with authorized outsiders and business partners of organization. This type of network helps to share details regarding inventory, pricing, product, purchase orders, support systems with selected outsiders such as vendors, customers, dealers, and so on.

While all three of these types of connectivity are essential from the enterprise viewpoint, most of the savings result from Remote Access VPN as the number of employees who travel and need to connect using long distance dial-up is showing an increasing trend and cost of remote access is decreasing.

Concerns of VPN

A potential problem of VPN is the fact that it uses the internet for connectivity. Since the Internet is a public medium, all communications between the LANs are visible to the outside world, and information is prone to interception or modification. So security plays an important role in the implementation of a VPN. To make sure communication between the LANs is not transparent to the outside world, proper encryption and authentication techniques should be used.
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