SMB shares moving traffic on PublicNet and ServiceNet
Cloud created by:
9 September 2017
Recently I was investigating an issue involving Windows 2012 servers and file transfers using SMB connections. When looking at the traffic between two Windows 2012 servers I found that an SMB connection was setup over ServiceNet but data moved over both ServiceNet and PublicNet networks. After researching this issue, I discovered this was a new feature of SMB 3.0 called SMB MultiChannel.
SMB MultiChannel is a performance feature that allows 2 connected servers to utilize multiple shared paths to transfer data. For cloud servers within the same region this means they could use paths such as ServiceNet and PublicNet. Unfortunately using the PublicNet for this traffic means that part of the file transfer will be metered which will result in additional bandwidth costs.
In order to prevent this you will want to disable SMB MultiChannel from inside of both Windows servers. When you have an active share setup you can run the command Get-SmbMultichannelConnection from the client server in Powershell.
I didn't find the right solution from the Internet.