When B replies the MAC address table becomes: Port HostĪnd the switch forwards the frame to port 0/1 – there is no need to flood now since the location of A is known. The switch populates it MAC address-table something like: Port HostĪnd floods the frame out of all other ports. Assume A is on port 0/1 and B is on port 0/2. Say a device ‘A’ with MAC (hereafter aaaa) sends a frame to device ‘B’ with MAC address bbbb. Switches learn where hosts are by examining the source MAC address in frames received on a port, and populating its MAC address-table with an entry for that MAC address and port. If this makes no sense, perhaps a quick summary of how switching at layer 2 works will help.
A MAC Flap is caused when a switch receives packets from two different interfaces with the same source MAC address.
