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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: Network end users to pull down 2 gigabytes a day, continuously?
On Tue, 9 Jan 2007, [email protected] wrote: Multicast streaming may be a big win when you're only streaming the top 5 or 10 networks (for some value of 5 or 10). What's the performance characteristics if you have 300K customers, and at any given time, 10% are watching something from the "long tail" - what's the difference between handling 30K unicast streams, and 30K multicast streams that each have only one or at most 2-3 viewers? 1/2, 1/3, etc the bandwidth for each additional viewer of the same stream? The worst case for a multicast stream is the same as the unicast stream, but the unicast stream is always the worst case. Multicast doesn't have to be real-time. If you collect interested subscribers over a longer time period, e.g. scheduled downloads over the next hour, day, week, month, you can aggregate more multicast receivers through the same stream. TiVo collects its content using a broadcast schedule. A "long tail" distribution includes not only the tail, but also the head. 30K unicast streams may be the same as 30K multicast streams, but 30K multicast streams is a lot better than 300,000 unicast streams. Although the long tail steams may have 1, 2, 3 receivers of a stream, the Parato curve also has 1, 2, 3 streams with 50K, 25K, 12K receivers. With Source-Specific Multicast addressing there isn't a shortage of multicast addresses for the typical broadcast usage. At least not until we also run out of IPv4 unicast addresses. There is rarely only one way to solve a problem. There will be multiple ways to distribute data, video, voice, etc.
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