February 21, 2018

Where is Internet Congestion Occurring?

In my post last week, I explained how Netflix traffic was experiencing congestion along end-to-end paths to broadband Internet subscribers, and how the resulting congestion was slowing down traffic to many Internet destinations. Although Netflix and Comcast ultimately mitigated this particular congestion episode by connecting directly to one another in a contractual arrangement known as paid peering, several mysteries about the congestion in this episode and other congestion episodes that persist. In the congestion episodes between Netflix and Comcast in 2014, perhaps the biggest question concerns where the congestion was actually taking place. There are several theories about where congestion was occurring; one or more of them are likely the case. I’ll dissect these cases in a bit more detail, and then talk more generally about some of the difficulties with locating congestion in today’s Internet, and why there’s still work for us to do to shed more light on these mysteries.
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