In layer 2 switching, the Ethernet frames should be received from the same port where it was sent, otherwise layer 2 switching or switching loop occurs.
Let me explain this concept with the topology depicted below (Figure -1).
Figure -1 VLAN load balancing
In the above figure, either Port 1 or Port2 is used to send the traffic, and the same port should be used to receive the traffic. The switches use MAC addresses to process the Ethernet frames. Read more