There are lots of reasons for Netflix to operate its own CDN. With its service accounting for such a high proportion of ISP traffic, it's better for it to have a direct relationship with them than work through companies like Akamai.
It also gives Netflix "end-to-end control" of its network, providing more opportunities to optimize the system. Its servers are purpose built for streaming movies, for instance, with the spinning disks carefully laid out to minimize "heat spots," or areas of overheating.
It also does lots of intelligent mapping in the network, to figure out the best location to stream each movie from. Netflix has close to 50 million streaming customers, in North America, South America and parts of Western Europe, and it's likely to expand further in future.
Netflix also uses Amazon Web Services, for tasks like running its website and its recommendations engine. Also, the movie studios upload their content to the Amazon cloud, where Netflix encodes it to its format before distributing it to its network.
"Whereas with Amazon we're a relatively small compute customer, on the CDN side we're a very large player," Fullagar said.
Only about 40 people work on the CDN, he said, with half working on software, 10 network engineers and 10 in operations.
Building the CDN wasn't without hiccups. Around the time Netflix started to roll it out two years ago, Thailand was hit by devastating floods that disrupted much of the world's hard disk supply. "I wouldn't say it derailed us, but it was problematic," Fullagar said.
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