Allyn defines some good requirements. However, he recommends using multicasting for scaling distribution of content. Multicasting has been a holy grail of scaling Internet content distribution for the last 15+ years. Unfortunately, it still generally doesn’t work over the Internet at large. Instead, to scale content delivery, one should use the model adopted by the Internet at large, CDN networks.

A CDN is a Content Delivery Network, described in more detail on wikipedia: http://en.wikipedia.org/wiki/Content_Delivery_Network

Now, for scaling to just a thousand or so remote locations, brute forcing transfers from a high speed data center will do, but for scaling to 10’s of thousands or more, a CDN service of some kind is probably required.

Thanks for the info Darren, much appreciated.

Darren is right, Multicast over the internet doesn’t happen.

The problem with CDN’s is there is always a propigation delay. While the delay can be low when engineered correctly, that higher tier of engineering means an increased cost.

Many large scale deployments either already have private terrestrial links back to their data centers, or utilize satellite connections for high bandwidth downloads. Both of those connections can easily support Multicast.

So yes Multicast over the internet doesn’t happen, but there are efficient, cost-effective, and very viable alternatives to expensive, low propigation-delay CDN’s.

In this article, there probably was not enough room for this level of detail.

I think you’re right Jordan. Multicast can and is implemented occasionally in private networks.

And you’re right, over satellite networks Multicast has a huge value! I wasn’t thinking about that. If IP multicast is integrated at the physical radio layer by your satellite provider, sending data from one satellite to many locations simultaneously is almost the only way to go.