An enterprise Layer 2 switch has Port 1 and Port 2 assigned to VLAN , and Port 3 assigned to VLAN . Port 1 receives an Ethernet frame with an unknown destination MAC address. Which of the following actions will the switch take upon receiving this frame?
- Flood the frame out Port 2 only, while updating the MAC address table with the source MAC address on Port 1 in VLAN .Answer
- BFlood the frame out Port 2 and Port 3 to ensure all devices physically attached to the switch receive the transmission.
- CConvert the Layer 2 frame into a Layer 3 broadcast packet and route it to all active switch interfaces.
- DStrip the 802.1Q header tag from the frame and forward it to Port 3 over the native VLAN interface.
Answer
The switch will flood the frame out Port 2 only while recording the source MAC address of the frame on Port 1 in VLAN 10.
When a Layer 2 switch receives an Ethernet frame with an unknown destination MAC address, it performs unknown unicast flooding. This operation forwards a copy of the frame out every port belonging to the same VLAN as the receiving port, except the port on which the frame arrived. Because Port 1 and Port 2 reside in VLAN 10, Port 2 is the only eligible forwarding destination. Furthermore, the switch updates its MAC address table with the frame's source MAC address mapped to Port 1 within VLAN 10.
Step-by-Step Solution
Key Concept
Layer 2 Unknown Unicast Flooding and VLAN Broadcast Domain Isolation