Virtual Private Networks
By: Scott Ayers
Transition From Leased Lines to VPNs
Quick History Lesson.
What is a VPN?
Leased Line Network Versus VPN
Example of a leased line network
ed Chicago Lin
•Leasing the lines 24 hours a day even though the line is not
•If one line breaks there is no redundancy.
•Expensive to lease.
Example of a VPN
VP N Public Network VPN
(ATM / FR /
Los New York
Virtual Private Network
•It is a shared network and therefore the costs are shared.
•The costs associated to a VPN are less than a leased line.
•There is great redundancy.
Leased Line Frame Relay VPN Internet VPN
Annual Charges $133,272 $89,998 $38,400
Installation $2,700 $5,760
Four VPN Appliances $16,000 $16,000
Total Cost, 1st Year $135,972 $111,758 $54,400
Prices are dated for the year 2000.
PPTP(Point-to- L2TP(Layer 2
point tunneling Tunneling
– Developed by many – Combination of PPTP
companies such as and Cisco’s L2F
Microsoft – Used for remote-access
– Designed for remote- and site-site
access – Operates at layer 2
– Operates at layer 2
IPSec(Internet SOCKSv5 with
Protocol Security) SSL-
– Suite of protocols that – SOCKSv5 is a standard for
provide secure tunneling of authenticating traffic across
IP packets only firewalls
– Use for site-to-site – SOCKSv5 with SSL allows
– Operates at Layer 3 for the creation of a VPN
– Integrated into IPv6 connection on any firewall
– It controls data at Layer 5
Advantages and Disadvantages
– Cost Savings – Uses the Internet
– Scalability Single point of failure
Uses the Internet Security concerns
– False Sense of Security
False Sense of Security
VPNs protect against eavesdropping and
VPNs do not protect against viruses or attacks
being passed through the VPN tunnel.
What do I need?
This Presentation and accompanying Research Paper
can be viewed at the following website: