The M-Lab study found significant congestion on some broadband providers' networks between early 2013 and early this year. In New York City, customers of Comcast, Time Warner Cable and Verizon saw drops in download speeds, in some cases down from 20 Mbps to 4 Mbps for extended periods.
But broadband provider Cablevison, which like the other three providers also uses Cogent's backbone to provide service, did not see similar congestion, suggesting that Cogent "had sufficient capacity" in at least part of its network, the study said. The traffic problems in New York City and some other cities abated in February at all the broadband providers experiencing problems, the study noted.
There were similar patterns in other cities. In Dallas and Los Angeles, customers of five large broadband providers saw massive congestion between February 2013 and February of this year, while customers of Cox saw no significant congestion, the study said.
Vint Cerf, a Google vice president and Internet pioneer, praised the M-Lab study, saying it suggests that business relationships between broadband and backbone providers were the source of the severe congestion.
The M-Lab study is "the first work of its kind, using open data and reproducible methods to expose complex performance issues at scale," Cerf said in a statement. "This research highlights the critical role of open data and transparent research in maintaining an accessible and open Internet: Without knowing the scope or extent of the problems, we cannot act to remedy them."
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