is it possible to multicast over internet? I think IGMP is not allowed by the ISPs, and also when the server sends stream to internet what is the upload bandwidth on the server side? thanks
It is possible to multicast over the internet certainly but by far the best way is if you have control of every piece between your servers and clients. I work for a company that has that control for around 30-40% of the country's ADSL links so have the option of using multicast - that's a luxury that not eveyone has. Oh and you can't predict the upload bandwidth from clients, you have to engineer that.
multicast over public internet will not work. you have choice of CDN with plenty of mirrors or using p2p-like approach where your clients become also relay nodes [ this will introduce additional latency, if you want to sort-of-multicast a movie - this works great - for instance voddler uses such approach where clients become 'seeding' nodes for other clients - this allows content provider to save distribution costs ].