Suppose you have to transfer a file of 99Mbit on a BOND of 3 VPN (3Mbit/s+3Mbit/s+10Mbit/s). Because the BOND in load balancing mode uses the round-robin scheduling to forward the packets, any VPN will forward 33Mbit of data. This means that this operation takes at least 33Mbit/(3Mbit/s)=11s to complete the file transfer. Hence the bandwidth of the BOND is 99Mbit/11s=9Mbit/s (without considering the overhead) that is the same of a BOND in which the 3 VPNs have the same speed.