A CDE Definition
See virtual private network.
virtual private network
A private network configured within a public network such as the Internet or a carrier's network. Years ago, virtual private networks (VPNs) obsoleted private lines between company branches. Using data encryption to maintain privacy, VPNs also allow mobile users access to the company LAN.
In the past, common carriers used their vast networks to "tunnel" traffic between customer locations to give the appearance of a private network while sharing backbone trunks, no different than the way the Internet works. Prior to the Internet's IP protocol, VPNs were built over X.25, Switched 56, frame relay and ATM technologies. See PVC, SVC, computer security and information security.
Internet VPNs are very popular, and several security protocols are used. IPsec, L2TP and PPTP provide secure tunnels over the Internet. For brief transactions at a website, SSL is widely used. See IPsec, L2TP, PPTP and SSL.
Virtual IP VPNs from Carriers
A "virtual private routed network" (VPRN) connects the customer's IP router to the provider's IP router. See MPLS.
Ethernet VPNs from Carriers
Carriers encapsulate Ethernet frames in one location and deliver them to another. Connecting two Ethernets is a "LAN interconnect service," while multipoint connectivity is a "transparent LAN service" (TLS). A "virtual private LAN service" (VPLS) is a multipoint VPN using an IP/MPLS core to route traffic. See TLS, VPLS and IP/MPLS core.
Frame Relay VPNs from Carriers
Carriers have offered frame relay point-to-point and multipoint VPNs, whereby the customer's equipment converts internal IP packets to frame relay packets. Adding a location in such a network means provisioning virtual circuits from the new site to all the other sites. See frame relay.
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