Starting with ONTAP 9.0, global network throttling is available for all SnapMirror and SnapVault transfers at a per-node level. This feature may be in a good use for your situation.
cluster_dst::> options -option-name replication.throttle.enable on
You can throttle incoming and outgoing traffic.
replication.throttle.incoming.max_kbs
replication.throttle.outgoing.max_kbs