Thank you very much for your reply.
Actually i only want is make an incremental backup both office.
On Office 1 make a copy to Office 2 same with Office 2 to Office 1.
My connection via internet (IPSec), bandwidth is 13 Mbps downstream/ 1 Mbps upstream (ADSL) both offices.
The type of data is transmit is only some office suite document.
For this what the best and ideal backup?