Ex Aspera user here. I worked in VFX, so I've been using aspera since before it was owned by IBM. Depending on what line speed you have, but for a gig link we

Ex Aspera user here. I worked in VFX, so I've been using aspera since before it was owned by IBM. Depending on what line speed you have, but for a gig link we made a simple protocol using parallel TCP streams. Basically, it chunked up the large file into configurable sized chunks, and assigned a chunk to each stream. Another stream passed the metadata. This has all the advantage of TCP, with less of the drawbacks of a custom UDP protocol. For transferring files from london to SF we were getting 800mbit/s over a 1 gig link.