Throughput is measured by total packets processed by CPU in any direction independently.

For example, if VOS processes 1 Gbps of traffic either in upload or download direction, it is considered as 1 Gbps throughput.

If 1 Gbps traffic comes on LAN and goes out on WAN or another LAN, it is just considered as 1 Gbps.

If VOS processes 1 Gbps upload and 1 Gbps download simultaneously, it is considered as 2 Gbps throughput. To give an example, users are uploading and downloading simultaneously at 1 Gbps in each direction.