What protocol is used to carry VLAN membership information across a trunk link?

What protocol is used to carry VLAN membership information across a trunk link?

• A. 802.3
• B. 802.11
• C. 802.1D
• D. 802.1Q

Answer: (D)

VLAN tagging on a trunk link is the way to carry VLAN membership information between switches. When traffic from multiple VLANs travels over a single physical link, a tag is added to each Ethernet frame that identifies which VLAN it belongs to. The standard that defines this tagging for Ethernet frames is 802.1Q. It inserts a small tag into the frame containing the VLAN ID, allowing the receiving switch to place the frame into the correct VLAN and forward it appropriately. The other options describe different technologies—802.3 is the basic Ethernet standard, 802.11 covers wireless networking, and 802.1D relates to Spanning Tree Protocol—none of which provide the VLAN tagging mechanism used on trunks.

VLAN tagging on a trunk link is the way to carry VLAN membership information between switches. When traffic from multiple VLANs travels over a single physical link, a tag is added to each Ethernet frame that identifies which VLAN it belongs to. The standard that defines this tagging for Ethernet frames is 802.1Q. It inserts a small tag into the frame containing the VLAN ID, allowing the receiving switch to place the frame into the correct VLAN and forward it appropriately. The other options describe different technologies—802.3 is the basic Ethernet standard, 802.11 covers wireless networking, and 802.1D relates to Spanning Tree Protocol—none of which provide the VLAN tagging mechanism used on trunks.