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Difficulty: EasyVLAN Configuration and 802.1Q Trunking

Match each IEEE 802.1Q trunking component or configuration parameter on the left with its correct operational behavior or definition on the right.

  • Native VLANCarries untagged frame traffic across an 802.1Q trunk link without adding a tag header.
  • 802.1Q HeaderInserts a 4-byte field containing a VLAN Identifier (VID) into the Ethernet frame.
  • Allowed VLAN ListSpecifies which VLAN traffic is permitted to traverse a switch-to-switch trunk link.
  • Access PortBelongs to a single VLAN and transmits untagged frames to connected end-user devices.

Answer

Native VLAN matches with carrying untagged frame traffic across an 802.1Q trunk link. 802.1Q Header matches with inserting a 4-byte field containing a VLAN ID into the Ethernet frame. Allowed VLAN List matches with specifying which VLAN traffic is permitted to traverse a trunk link. Access Port matches with belonging to a single VLAN and transmitting untagged frames to end-user devices.
Each key trunking component maps directly to its operational definition: the Native VLAN handles untagged trunk frames, the 802.1Q header inserts a 4-byte tagging field, the allowed VLAN list restricts allowed VLAN IDs on a trunk, and an access port connects end devices to a single untagged VLAN domain.

Step-by-Step Solution

1
Identify the function of Native VLAN on 802.1Q trunks.
Native VLAN carries untagged traffic over trunk links without modification.
By definition in 802.1Q, frames originating on the native VLAN do not receive a 4-byte VLAN tag when crossing a trunk link.
2
Identify the structure and purpose of the 802.1Q header.
802.1Q inserts a 4-byte tag into the frame header to identify the destination VLAN ID.
Trunk interfaces use tagging to multiplex frames from multiple VLANs over a single physical link.
3
Identify the purpose of the allowed VLAN list configuration.
Allowed VLAN list restricts which VLANs can pass traffic across the trunk link.
Pruning or specifying allowed VLANs prevents unnecessary broadcast and unicast traffic for unneeded VLANs from traversing the trunk.
4
Identify the characteristics of an access port.
Access ports belong to a single VLAN and carry untagged frames for endpoint connectivity.
End-user devices such as PCs or printers do not understand 802.1Q VLAN tags, so access ports strip tags prior to frame egress.

Key Concept

VLAN Configuration and 802.1Q Trunking Fundamentals
Estimated Time:1m 0s
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Topics

VLAN Configuration and 802.1Q Trunking

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