Two Physical LANs: Broadcasts Do Not Leave the Originating LAN

Note that with two switches, each switch has its own address table. When Fred sends a broadcast, switch1 forwards it out all other portsin this case, only to Barney. Switch2 does not receive a copy of the broadcastin fact, there is not even a physical cable conneting the two switches in this case.

Because the two switches have created two separate VLANs, both broadcast frames and unicast frames from the top LAN cannot be forwarded to the bottom LAN. For instance, if Fred were to send a frame with a destination address of 0200.3333.3333 (Wilma), switch1 would not have Wilma's address in its address table. Figure 7-4 summarizes the logic.