I work in financial data — lots of big ol’ UDP multicast streams getting replicated by big routers in private data centers on private lines. In that context, e

I work in financial data — lots of big ol’ UDP multicast streams getting replicated by big routers in private data centers on private lines. In that context, everything bad can happen, but it rarely does. For example: packets most definitely get dropped, but not every packet does in practice. Packets can get double-sent, but again, not every packet in practice. Packets can get corrupted randomly, but again, not every packet in practice. The hard mathematical guarantee: nothing at all! You will get a packet from 0 to N times, where N might be arbitrarily large. The in-practice behavior: mostly kinda works, but be careful! Have a strategy for reordering, a strategy for detecting and handling dupes, and a strategy for when you need to just give up and start from scratch. The internet is like that but if some router is screwing it up, you can’t call the owner and complain.