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Difficulty: EasyVLAN Configuration and 802.1Q Trunking

A network administrator is configuring an IEEE 802.1Q trunk link between two managed switches to carry traffic for multiple VLANs over a single physical cable. Which of the following statements correctly describe the default operation and frame structure of IEEE 802.1Q trunking? (Select TWO.)

  1. Frames associated with standard tagged VLANs have a 4-byte header containing the VLAN ID inserted into the Ethernet frame.Answer
  2. Frames belonging to the native VLAN are transmitted across the trunk link without an 802.1Q header tag.Answer
  3. C
    Trunking enables hosts on different VLANs to communicate with each other directly at Layer 2 without requiring a router.
  4. D
    Untagged frames received on an 802.1Q trunk interface are automatically assigned to VLAN ID 4095.

Answer

IEEE 802.1Q trunking inserts a 4-byte tag into frames for tagged VLANs and transmits native VLAN frames without an added VLAN header tag.
IEEE 802.1Q trunking operates by inserting a 4-byte header tag into standard Ethernet frames to identify VLAN membership across switches. Traffic belonging to the native VLAN is transmitted untagged by default.

Step-by-Step Solution

1
Identify how IEEE 802.1Q maintains VLAN separation across a trunk link.
A 4-byte VLAN header tag is inserted into Ethernet frames belonging to tagged VLANs.
The receiving switch reads this tag to determine which VLAN broadcast domain the frame belongs to.
2
Identify how IEEE 802.1Q handles native VLAN traffic.
Frames on the native VLAN are sent across the trunk link without a tag.
Native VLAN support allows untagged legacy traffic or control frames to pass across trunk interfaces.

Key Concept

802.1Q Frame Tagging and Native VLAN Operation
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Topics

VLAN Configuration and 802.1Q Trunking

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