I have a computer connected to an unlabeled RJ-45 port. Because it is not labeled, I do not know which switch port the computer is plugged into.
My initial thought was that I could login to the Catalyst switch and run the following command to find the switch port:
sh mac add | inc <MAC>
However, the computer's MAC address is not appearing in the MAC address table of the switch, despite the fact that the computer has a link light (and thus, must be physically connected to the switch). The computer is autoconfiguring a 169.254.x.x address because it cannot find a DHCP server. I suspect this is because the specific VLAN that is configured on the switch port doesn't have access to a DHCP server.
I tried manually configuring a few static IP addresses on the computer, and that seemed to make no difference in terms of getting the computer's MAC address registered in the switch's MAC table. I was trying random static IP addresses because I do not know to which subnet the VLAN is associated.
My question: does this mean that a connected device, like a computer, must have a valid IP address within the correct subnet to register its MAC address to the switch's MAC table? Until today, I thought a mere physical connection was sufficient to register a MAC address to a switch's MAC address table.