Unfortunately the cost saving from multicast assumes a traditional IP network. In this respect DSL still looks like dial-up did, with every subscriber at the end of a PPP connection. An ISP gets a whole pile of point-to-point links from a nearby POP. The physical infrastructure is largely hidden from ISPs, so there is no way to save money on the expensive long-haul. If you've got data in London, and it needs to go to 600 subscribers in Cardiff, you have to send and pay for 600 copies of the data.
Posted Feb 18, 2013 16:35 UTC (Mon) by butlerm (subscriber, #13312)
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For IP multicast to be useful on a large scale, it must be implemented by the last mile ISP. That is easy enough though - locate a distribution node on the ISP network, unicast across the backbone to it, and then multicast from it to the ISP customers. Every wireline television system in the world is likely to look like this in a few years. Television meaning real time, not stored content distribution.