I'm seeing an issue with a computer (running an embedded OS) transmitting over a network to an XP embedded machine.
The computer has 10 physical ethernet ports, 9 of which are on this network. I have assigned in the application, each eth port to be a unique address, and have verified when I do an "ifconfig" that each physical port has a unique mac address as well.
When I do a wireshark capture, I see that all the packets going out of the computer correctly transmit from 9 different IP addresses. However, they all have the same exact MAC address when sending. On the other hand, when the XP embedded machine responds with TCP acks, each ack packet is correctly paired with a unique IP and unique MAC address.
In summary: 9 packets sent from 9 different/unique physical ethernet ports on the same computer. They all have the same source mac address. 9 acks come back, each addressed to the unique 9 IP addresses and unique 9 MAC addresses.
Is this common? From what I can tell, the application is not doing this. And I doubt it is being done in the driver because another machine running the same driver with the same cards does not have this behavior.