Storage Node -- just SMB/CIFS with some other async stuff?

Greetings,

I'm a longtime TI user, both Server and Workstation in unmanaged scenarios, thinking for the first time about what I could do with a Storage Node over our 5Mbps WAN.

My principal question is whether the SN uses any special (i.e. optimized) TCP protocol for backups themselves or whether those still run over standard SMB/CIFS -- I couldn't get a clear answer from prior posts. I wouldn't try to write to a plain Windows share over our rather slow WAN due to the known overhead, but our rate-of-change (incremental) is rather small (2 GB/day) and could see squeezing an incremental backup over the WAN link IF there is a more streamlined protocol (beyond the usual TI compression, which is of course also essential).

So what's the deal there?

P.S. I know the cloud backup obvs. uses some special protocol, but cloud in the middle is of no use for us (need the backup to already be at our location on the other coast).