>These dumb pipes use QUIC over a magic socket. It may be dumb, but it still has all the features of a full QUIC connection: UDP-based, stream-multiplexing and encrypted.

How is multiplexing used here? On the surface it looks like a single stream. Is the file broken into chunks and the chunks streamed separately?

In this particular example there is no multiplexing. It's just one QUIC stream.

In other iroh based protocols the ability to have many cheap QUIC streams without head-of-line blocking is very useful. E.g. we got various request/response style protocols where a large number of requests can be in flight concurrently, and each request just maps to a single QUIC stream.