AT&T, Verizon and tw telecom held down the top three spots, respectively, in Vertical System Group's 2011 U.S. Business Ethernet Leaderboard, while Cox Communications ranked fourth overall.

VSGThe Leaderboard ranked the service providers that hold 4 percent or more of the billable Ethernet port installations in the United States. Following Cox, in order, were XO, CenturyLink (including Qwest and Savvis), Time Warner Cable, Level 3 (including Global Crossing), and Cogent.

The following six service providers comprised the next "challenge-tier" of the U.S. Ethernet market based on port share (in alphabetical order): AboveNet, Charter Business, Comcast Business, Optimum Lightpath, Reliance Globalcom and Windstream.

Other providers delivering Ethernet services in the U.S. included: American Telesis, Bright House Networks, Cincinnati Bell, Expedient, FiberLight, Frontier, Integra, Lightower, Masergy, Megapath, NTT America, Orange Business, Sidera Networks, SuddenLink, Virtela and Zayo Group.

"The second half of 2011 saw solid follow-through of new network rollouts and add-on deployments. High-speed service availability and decreased pricing were major market drivers," said Rick Malone, principal at Vertical Systems Group. "Our research also shows a clearer stratification among providers competing for Ethernet business in the U.S. The Leaderboard companies comprise the top tier of the market, accounting for a combined total of more than three-quarters of U.S. Ethernet service ports.

"The challenge-tier providers have attained market presence just below the Leaderboard threshold. Numerous other providers are also selling or planning to offer Ethernet services in the U.S."

Vertical's year-end market analysis found that Ethernet port growth for 2011 was 31 percent. Market shares for the U.S. Leaderboard were calculated using the base of enterprise installations of Ethernet services, plus input from Vertical's surveys of Ethernet service providers.