How to generate traffic between network interfaces of one machine?

Question

ubuntu

Good afternoon.
There is a ubuntu server. 10 network cards. I can use it to generate traffic using iperf to other servers.
At the moment, the task is to connect 2 ports directly and generate a traffic flow between them. In between there will be a hub device. The idea is to make sure that the hub can pass traffic through itself and measure the speed.
The main problem I do not understand how it should look like. Ip from one network on different interfaces I cannot hang up. How do I specify that traffic should exit one interface and be received on another?
Is there a program or technology?

Answer 1

Output different interfaces to different netns and inside netns hang up respectively different addresses from the same subnet and start the traffic generator.

Answer 2

take advantage of this??

-B, --bind host bind to a specific interface