[georgelyon]

I ran into this problem a while back working at a company that was working to distribute video streams with low latency (lower than Low-Latency HLS) to a large number of viewers. Initially a prototype was built on top of AWS with fan-out/copying and it was terrible. This was partially due to inefficiency, but also due to each link being a reliable stream, meaning dropped packets were re-broadcast even though that isn't really useful to live video.

Moving to our own multicast hardware not only greatly improved performance, but also greatly simplified the design of the system. We required specialized expertise, but the overall project was reasonably straightforward. The biggest issue was that now we had a really efficient packet-machine-gun which we could accidentally point at ourselves, or worse, can be pointed at a target by a malicious attacker.

This 1-N behavior of multicast is both a benefit and a significant risk. I really think there is opportunity for cloud providers to step in and provide a packaged solution which mitigates the downsides (i.e. makes it very difficult to misconfigure where the packet-machine-gun is pointing). My guess is that this hasn't happened yet because there aren't enough use-cases for this to be a priority (the aforementioned video use case might be better served by a more specialized offering), but exchanges could be a really interesting market for such a product.

It would be pretty efficient to multi-cast market state in an unreliable way, and have a fallback mechanism to "fill in" gaps where packets are dropped that is out-of-band (and potentially distributed, i.e. asking your neighbors if they got that packet)