I'm trying to understand the specifics of trunking a VLAN on two switches.
Say I have two switches, both hosting half of VLAN 3.
Switch 1: Ports 0-5 on VLAN 3, Port 6 is Trunk
Switch 2: Ports 0-5 on VLAN 3, Port 6 is Trunk
Do the two switches know what the MAC addresses are of the devices connected to the other switch which are in the same VLAN, or do the switches just know that Port 6 is a VLAN 3 trunk and when they receive a broadcast frame, they just flood the frame to the trunk port with the VLAN tag and expect the switch on the other end to deal with it?
Best Answer
When a frame enters a switch, the switch will take the source MAC address and update its MAC address table with the interface where the frame entered the switch. That interface can be an access or trunk interface.
Broadcast or unknown unicast frames will be sent to all interfaces (except the one where the frame entered the switch), including access and trunk interfaces.
Known unicast frames will be sent to the switch interface indicated in the switch MAC address table, whether an access or trunk interface.