With this development, security has become a major
concern for traffic traversing the shared medium. Cryptographic techniques evolved with dedicated protocols
and standards to protect the privacy of traffic. These protocols and standards are rapidly growing in popularity
and are increasingly being used by customers and service providers. Traffic is secured using encryption
technology in a secure tunnel between the communicating peers. These are called secure VPNs.
Secure VPNs are commonly used to replace or augment existing point-to-point networks that utilize dedicated
leased circuits or WAN networks over Frame Relay and ATM circuits.
Secure VPN technologies include
IPsec
L2TP over IPsec
SSL encryption
This chapter primarily focuses on IPsec Secure VPN.
Trusted VPN (Non-Cryptographic VPN)
The major characteristic of Trusted VPN is that it enables the service provider to offer a dedicated leased circuit
or channel to a customer. Hence, pseudo point-to-point communication occurs in this scenario, thereby allowing
networks to peer directly by using a dedicated leased circuit. This technique provides a sense of security and
data privacy. When traffic traverses these dedicated point-to-point circuits, you have what is called a Trusted
VPN.
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