Outside of the XC-clusters (they have a switch dedicated to load-balancing), the route the traffic takes through either sensor in a pair is decided by the network, not the sensor. When configured in a HA pair the sensors will share state information, so they can both handle asymmetric traffic without any issues. If one sensor does go down, your network will need to be able to switch traffic, as the failover cable connection is only for sharing state information, not traffic.
Thank you msitko !
So if all traffic is going through only one of the Active Sensors, it is because the network is not sending traffic to the other sensor.
If we want to send half traffic through each sensor we must load balance in the network right?
And also, if we already have connections established, we cannot "move" the connections that already established from one sensor to the other one.
Yep - The sensor is just an extention of the wire, it doesn't do any routing since traffic can only go in and out each port pair so you'll need to configure the supporting network equipment to take care of the routing. Since the sensors are in HA, they would be able to handle connections that start on one sensor and move to another.