Why YouTube buffers: The secret deals that make—and break—online video | Ars Technica: Excellent analysis including on CDN siting in ISP data centres: "In addition to peering with network operators, Google has what it calls the "Google Global Cache (GGC)." This "represents the final tier of Google’s content delivery platform and is closest to users," Google says in its description of the service. "With GGC, network operators and Internet Service Providers deploy a small number of Google servers inside their network to serve popular Google content including YouTube. Google's traffic management system directs users to the node that will provide the best performance for the user. GGC can be located anywhere in an operator's network to maximize savings in backbone and transit bandwidth. Targeted deployment can reduce the number of route-miles traveled on an operator's network to serve Google traffic, further increasing cost savings for the operator."
Google does not reveal which ISPs accept the equipment into their data centers. It's clear many do not, since ISPs have argued that Google and Netflix should be paying them, even though the caches are offered for free.
Netflix's similar peering and caching service is called Open Connect. ISPs can peer with Netflix at up to eight Internet exchange points for free "or can save even more transit costs by putting our free storage appliances in or near their network," Netflix says. Frontier, British Telecom, TDC, Clearwire, GVT, Telus, Bell Canada, Virgin, Cablevision, Google Fiber, Telmex, and RCN are among those who have done so.
"To us, it's really a black box that's run by Netflix," RCN VP of network services Peter Jacoby told Ars. "We do almost nothing except give it IP addresses. We put them in our data centers and that content gets a lot closer to our customers, so when they request a movie, typically the popular ones I'm told will stream from their closest cache and that eliminates a lot that can go wrong between them and Netflix."" 'via Blog this'