I was reading a text book, it says suppose a host A sends a frame with destination address DD-DD-DD-DD-DD-DD arrives at the switch on interface x. The switch indexes its table with the MAC address DD-DD-DD-DD-DD-DD, and if There is an entry in the table, associating DD-DD-DD-DD-DD-DD with interface x. In this case, the frame is coming from a LAN segment that contains adapter DD-DD-DD-DD-DD-DD. There being no need to forward the frame to any of the other interfaces, the switch performs the filtering function by discarding the frame.
I have a question in regards to this case:
- if A's frame arrives at interface x which also associates with A's MAC address, which means A is sending a frame to itself, why a host need to send frames to itself?