CenturyLink is on a roll when it comes to U.S. Ethernet carrier services.

For two years running, the communications giant has topped Vertical Systems Group’s (VSG) year-end U.S. Carrier Ethernet Services Leaderboard.

CenturyLink powered its way to the top spot in the year-end 2017 leaderboard after its acquisition of Level 3 Communications. Now it’s taken the top spot on the year-end 2018 leaderboard, followed by AT&T, Verizon, Spectrum Enterprise, Comcast and Windstream.

AT&T led the benchmark ranking from 2005-2016. Cox dropped out of the leaderboard and into VSG’s challenge tier on slower-than-market port growth.

VSG calls this an industry benchmark for measuring Ethernet market presence. Network providers must have 4 percent or more of the U.S. Ethernet services market to crack the leaderboard.

“Despite its relative maturity, the Ethernet market continues to expand at a healthy pace,” said Rick Malone, VSG principal. “U.S. port installations grew more than 12 percent in 2018, in line with our forecasts. However, revenue growth is not keeping pace with port growth due to falling prices and changing service mixes. One notable catalyst is the deployment of SD-WAN, which is resulting in customers shifting from switched Ethernet services to dedicated internet access.”

U.S. retail Ethernet customer installations grew to more than 1.1 million ports, up 12 percent from year-end 2017. The two cable multiple system operators (MSOs), Spectrum and Comcast, had the highest port growth in the second half of 2018.

Altice USA, Cogent, Frontier, GTT, Sprint and Zayo join Cox in the challenge tier, which includes providers with between 1 and 4 percent share of the U.S. retail Ethernet market.

The market-player tier includes such companies as BT Global Services, Crown Castle Fiber, FiberLight, Masergy, NTT America, Orange Business and TPx.