Notice that there are bi-directional traffic in a link. Therefore, ‘Throughput’ is calculated as the total sum of all WAN’s inbound and outbound bandwidths.
Example:
(in bps)
WAN1: 6M/1M (Downlink/Uplink) DSL
WAN2: 3M/1M Cable
WAN3: 10M/10M Metro Ethernet
Throughput requirement = (6+1)+(3+1)+(10+10) = 31M