CenturyLink has claimed the top spot on a second U.S. Ethernet carrier services benchmark.

CenturyLink, AT&T and Verizon took the top three spots on Vertical Systems Group’s year-end 2018 U.S. Incumbent Carrier Ethernet Leaderboard, an industry benchmark for measuring Ethernet market presence. Windstream, which filed for chapter 11 bankruptcy protection last week, and Frontier ranked fourth and fifth.

Incumbent carriers are facilities-based telecom companies, including interexchange carrier (IXC) and LEC providers.

CenturyLink, AT&T, Verizon and Windstream each hold a top rank on the year-end 2018 U.S. Carrier Ethernet Leaderboard, while Frontier is in the “Challenge Tier” for 2018.

The incumbent carrier segment accounted for more than half of the more than 1.1 million retail Ethernet customer ports installed in the U.S. at the end of 2018.

Other companies in the incumbent sector include Alaska Communications, Cincinnati Bell, TDS Telecom and other local and regional incumbents.

The year-end 2018 U.S. Cable Multiple Systems Operators (MSO) Ethernet Leaderboard includes Spectrum Enterprise in the top spot followed by Comcast, Cox and Altice USA. This benchmark ranks companies based on U.S. retail port share for this segment.

Spectrum Enterprise and Comcast each hold a top rank on the year-end 2018 U.S. carrier Ethernet leaderboard, while Cox and Altice USA are each in the Challenge Tier. Comcast and Spectrum Enterprise had the highest Ethernet port growth during 2018.

Other companies in the cable MSO segment include Armstrong Business Solutions, Atlantic Broadband, BendBroadband Business, Cable One Business, MediaCom, Midco, RCN Business, WOW!Business and other cable companies selling retail U.S. Ethernet services.

The year-end 2018 U.S. Competitive Provider Ethernet Leaderboard includes Cogent in the top spot followed by Zayo, GTT and Sprint. To qualify, companies must have either a top rank or be in the Challenge Tier on the U.S. carrier Ethernet leaderboard.

For the second consecutive year, there were no competitive providers with a top rank on the leaderboard.

Other companies in the competitive provider segment include Crown Castle Fiber, Expedient, FiberLight, FirstLight, Fusion, Masergy, MegaPath, MetTel, NTT America, Orange Business and TPx.