[e2e] P2P Streaming alternatives??

[hsanson]

I have been researching on scalable real time streaming architectures 
and everybody seems to be betting on P2P streaming. If you see the 
current alternatives then the P2P streaming idea does not look so bad.

- Classic server/client architecture simply accept as many clients as 
server resources allow and refuse connection to any new clients.

- Content Delivery Network, increase capacity as needed by adding more 
servers to the CDN, that is costly and normally wastes those resources 
on non peak times.

- IP multicast, that would be the optimal solution but as I understand 
only works on corporate environments and so far will never expand to 
cover the Internet.

- P2P sounds like the perfect solution, keep enough resources to serve a 
few clients and in peak sessions use client resources to distribute the 
media. As demand increases so the available resources (bandwidth) increase.

But the technical challenges we need to overcome in order to enable P2P 
streaming are too high:

  - dynamic clients can disrupt others connections.
  - security, any client can inject other data to the stream.
  - heterogeneous clients, not all clients have equal capacity.
  - P2P distributed, scalable and fast management algorithms.

So I wonder if there exist any other alternative to cheap, scalable 
media streaming apart from the architectures mentioned above? or shall I 
focus my research somewhere else.

comments are welcome,
Horacio