When you are pushing terabytes of weights to hundreds of GPU nodes, unicast stops being a solution. Here is what actually works — and where multicast still struggles.The Problem Engineers Hit at ScaleIf you have ever watched a 70-billion-parameter model take 20 minutes to load across a 200-node inference cluster, you have felt this problem in practice. The culprit is almost always the same: the model server opens a separate TCP stream to each receiver, saturating its own NIC before the first node finishes loading.