virtual private network

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virtual private network

[¦vər·chə·wəl ‚prī·vət ′net‚wərk]
(communications)
A wide-area network whose links are provided by a common carrier although they appear to the users to behave like dedicated lines, and whose computers use a common cryptographic key to send messages from one computer in the network to another. Abbreviated VPN.

Virtual Private Network

(networking, security)
(VPN) The use of encryption in the lower protocol layers to provide a secure connection through an otherwise insecure network, typically the Internet. VPNs are generally cheaper than real private networks using private lines but rely on having the same encryption system at both ends. The encryption may be performed by firewall software or possibly by routers.

Link-level (layer 2 and 3) encryption provides extra protection by encrypting all of each datagram except the link-level information. This prevents a listener from obtaining information about network structure. While link-level encryption prevents traffic analysis (a form of attack), it must encrypt/decrypt on every hop and every path.

Protocol-level encryption (layer 3 and 4) encryption encrypts protocol data but leaves protocol and link headers clear. While protocol-level encryption requires you to encrypt/decrypt data only once, and it encrypts/decrypts only those sessions that need it, headers are sent as clear text, allowing traffic analysis.

Application (layer 5 up) encryption is based on a particular application and requires that the application be modified to incorporate encryption.

Cisco.

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
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.
References in periodicals archive ?
I look forward to leading Blue Ridge Networks' team and enhancing its leadership position in the Virtual Private Networking arena.
Blue Ridge Networks provides outsourced Virtual Private Networking solutions enabling highly secure private communications over the Internet.
Blue Ridge Networks, a leading provider of outsourced Virtual Private Networking (VPN) solutions, and AB&T Telecom, a leading provider of communication products and services, today announced a partnership that will provide Blue Ridge Network's VPN technology to AB&T's extensive list of telecommunication service resellers.
Blue Ridge Networks provides high security Virtual Private Networking solutions enabling private communication over the Internet.
Blue Ridge Networks, a leading provider of outsourced Virtual Private Networking solutions, announces the addition of Mark Pugerude as Vice President of Sales to its growing executive management team.
Square One, founded in 1987, is a full-service technology consulting firm offering a complete line of project-based and contract services including: network design, network and data security, virtual private networking and complete project management services.

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