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 ?
UK ISP Zen Internet launched on Monday (23 July) an IP VPN Wide Area Networking solution to meet the requirements of multi-site business customers.
Frost & Sullivan has put the predicted growth down to IP providers releasing the potential of IP VPN and the fact the companies are starting to migrate their networks from Frame Relay and Asynchronous Transfer Mode (ATM) to IP VPN as the benefits become apparent.
Enterprises can use IP VPN services to replace leased lines for interconnecting company sites, or to provide telecommuters and mobile workers with remote access to the corporate LAN.
The IP VPN market in Asia Pacific grew at a CAGR of 10% between 2008 and 2010.
Additionally, several vendors and noncarrier IP VPN providers have developed new IP VPN products and services, or improved earlier versions during the past year.
Learn how the market for IP VPN services in North America will evolve over the next five years.
Learn how the market for IP VPN services in Singapore will evolve over the next five years.
The forecast allows service providers and vendors to quantify the market for IP VPN services for 50 countries.
The adoption of IP VPN and Network Convergence is growing within the government sector.
IP VPN technology has an established base within US healthcare and represents an important segment of today's data services.
We also see limited IP VPN deployment, but discusses the extent to which they are replacing existing WAN services.
com/reports/c72405) has announced the addition of "US IP VPN Market Update" to their offering.