The answer to this is slightly complicated.
We have an extensive auto-mounter script that lives in /etc/auto.plutoStorageDevices.
This script does database lookups to determine how to mount a particular directory.
sometimes, NFS mounts to the MD are used, sometimes SMB mounts are used. This is determined by the device template # of the share in the device tree.
If you copy a file to \\dcerouter, then it all filters through samba, because samba is running on the core, and the file accesses are therefore going through the core, and the automounter is mounting remote shares as NFS or SMB as appropriate.