Virtual Private LAN Service-VPLS

摘要

Recently virtual private LAN service (VPLS), an emerging subset of technologies, has generated a lot of interest in the telecom industry as one of the alternatives for creating virtual private networks (VPNs). By definition, VPLS, also known as transparent LAN service, or virtual private switched network service, is a case of Layer 2 VPN service distinguished by the support of Layer 2 broadcast. VPNs allow corporate users to secure pipes through public networks [1]. VPLS can enable a private corporate Ethernet network to be extended over a provider-managed IP or MPLS (multi protocol label switching) network infrastructure. This type of service will enable service providers to connect multiple corporate customer sites/edge devices with all locations appearing to be on the same network, and without the complexity of configuring Layer 3 routers. VPLS also extends the broadcast and multicast services of Ethernet into MPLS, enabling multipoint VPNs with true transparency to the corporate user. A virtual private LAN appears in (almost) all respects as a LAN to customers of a service provider. However, in a VPLS, the customers are not all connected to a single LAN; the customers may be spread across a metro or wide area. In essence, a VPLS glues several individual LANs across a metro area to appear and function as a single LAN.