Transferring a file across multiple sockets is faster than just using a single socket?

Question

This old project (since 2002) says that if you split a file into several pieces, and then transferred each fragment using a different socket, it will arrive much faster than transferring it as a whole using one socket. I also remember reading (many years ago) that some download manager also uses this technique. How true is this?

Answer 1

Given that a single TCP connection with large windows or small RTT can saturate any network link, I don’t see what benefits you expect from several TCP sessions. Each new part will start with a slow start and, therefore, will have a lower transfer rate than the established connection.

TCP already has code for high-performance, high-latency connections (the " window scale option ") and packet loss processing. Attempting to improve this with parallel connections will usually have a negative effect if there are more errors during failures and packet loss is increased (due to congestion that TCP can manage on one connection).

TCP , , (, bittorrent), ( , TCP ).