Reduce Network Bandwidth
vSphere Replication copies only changed data to the recovery site to lower bandwidth utilization, improve network efficiency and enable more aggressive recovery point objectives (RPOs) than a manual, full-system copy. With vSphere Replication, you can:
Utilize a “seed copy” of virtual machine data for the initial synchronization to reduce the amount of time required to create the initial copy
Ensure efficient network utilization by tracking changed disk areas and replicating only those changes
Optionally enable data compression to further reduce network bandwidth consumption
- See more at: http://www.vmware.com/products/vsphere/features/replication#sthash.jaJGNSG3.dpuf