ABSTRACT
In this chapter, we look at some basic message integrity technologies, i.e., technologies that are used to ensure that the received message has not been unintentionally altered
en route
compared with the originally sent message. Ensuring message integrity is also called
message authentication
as opposed to
user authentication
described in Chapter 3. One way to attain a high degree of confidence that each message is
sent and received with integrity in any network infrastructure, including a shared one like the Internet, is to make the communication link behave like a private line circuit. In this regard, the most basic approach is to use Layer 2 virtual private network (VPN) technologies to ensure the separation of traffic in the network. Layer 2 VPNs are based on the use of hop-to-hop identifications such as data-link control identifiers (DLCIs) in Frame Relay (FR
)
permanent virtual circuits (PVCs) and virtual path identifiers or virtual circuit
identifiers (VPI or VCIs) in Asynchronous Transfer Mode (ATM) to achieve separation of traffic over the entire virtual connection.
