Current Physical Node ID

The current physical node ID is shown if a card has been set up to "spoof" the ID of another card. Basically, a parameter is passed to the driver telling it that the node's ID is actually the value that appears. Depending on the card, some drivers will accept this. What spoofing does on a higher (software) level, is filter out the packets that were meant for this node ID. This method is considerably slower than if you let the card filter out the packets on a hardware level. Because the card is set in promiscuous mode, it has to accept all packets that come in and use a software mode to sort them.

Another way of thinking about this is to compare it to a postal system, where if we wanted to "pretend" to be someone else, we would accept all mail from the Post Office. However, we would then have to sort all the mail. This would take a much longer time compared with the amount of time the Post Office would take to presort the mail, and give us only the mail addressed to us. For more information, see "Promiscuous Mode," below.