A Cisco switch receives an untagged Ethernet frame on an IEEE 802.1Q trunk link and forwards it out another 802.1Q trunk link. Arrange the operational steps in the correct order from initial frame arrival to final frame transmission.
- 1An untagged Ethernet frame arrives at an active switchport configured as an IEEE 802.1Q trunk.
- 2The switch assigns the untagged frame internally to the native VLAN configured on the ingress trunk port.
- 3The switch performs a Layer 2 MAC address table lookup within the context of the native VLAN to determine the egress port.
- 4The switch transmits the frame out the egress trunk interface untagged because the destination interface native VLAN matches the frame's VLAN.
Answer
The correct operational sequence begins with the arrival of an untagged Ethernet frame on an 802.1Q trunk port, followed by internal mapping to the ingress port's native VLAN, executing a MAC address table lookup within that native VLAN, and finally transmitting the frame untagged out an egress trunk configured with a matching native VLAN.
IEEE 802.1Q trunks handle untagged traffic by implicitly classifying ingress frames into the configured native VLAN. The switch uses that native VLAN's MAC address table for forwarding decisions and sends the frame out an egress trunk untagged if the egress interface shares the same native VLAN configuration.
Step-by-Step Solution
Key Concept
IEEE 802.1Q Native VLAN Ingress and Egress Processing Mechanics