AT&T is the top dog on Vertical Systems Group’s latest business Ethernet services leaderboard, while Cox Communications and Time Warner Cable were ranked fifth and seventh, respectively.

Vertical Systems Group’s “Mid-2012 U.S. Business Ethernet Leaderboard” ranks the service providers that accounted for 4 percent or more of the market based on billable enterprise port installations.

Verizon ranked second on the leaderboard, followed by tw telecom, CenturyLink, Cox, XO, Time Warner Cable and Level 3. Cox was previously ranked fourth in the leaderboard rankings, while Qwest, which is now owned by CenturyLink, was ranked fifth.

AT&T, Verizon and tw telecom have ranked first through third, respectively, for the past several years.

“New value-added service enhancements and improved network quality fueled the solid growth many Ethernet providers experienced in the first half of this year,” said Rick Malone, principal at Vertical Systems Group. “Additionally, our research clearly indicates rising demand for Ethernet access focused on connectivity to private clouds for data center hosting. We expect to see increased deployments of these configurations, which could have an impact on Ethernet share results as early as year-end 2012.”

Other providers selling Ethernet services in the U.S. were segmented into two tiers, as measured by share of ports installed. The first or “Challenge” tier for mid-2012 included the following seven Ethernet service providers (in alphabetical order): Charter Business, Cogent, Comcast Business, Optimum Lightpath, Reliance Globalcom, Windstream (includes Paetec) and Zayo Group (includes AboveNet).

The second or “Market Player” tier covered all other providers offering U.S. Ethernet services. The Market Player tier consisted of the following companies (in alphabetical order): Alpheus Communications, American Telesis, Bright House Networks, Canby, Cincinnati Bell, Consolidated Communications (includes SureWest), Expedient, FiberLight, Frontier, Integra, IP Networks, Lightower, Litecast, LS Networks, Masergy, Megapath, Met-Net, NTT America, Orange Business, Sidera Networks, Spirit, Sprint, Suddenlink, U.S. Signal, Virtela and others.

Market shares for the leaderboard were calculated using Vertical’s base of enterprise installations, plus direct input and other data from surveys of Ethernet service providers.