The recent announcement by Verizon (NYSE: VZ) that it plans to roll out Virtual Private LAN Services (VPLS) starting in March highlights the continued demand for Ethernet WAN services (whether metro or long-distance).

Verizon (which provided few details, other than announcing availability of its service) joins AT&T (NYSE:T), which has limited deployments in about 20 cities, and alternative providers Masergy and Broadwing, both of whom offer VPLS services. (Masergy was the first to deploy VPLS services in the United States in 2003).

Based on the multiprotocol label switching specification (MPLS) developed by the Internet Engineering Task Force (IETF), VPLS addresses some of the specific challenges with extending Ethernet across the WAN, most notably scalability and availability.

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