A network technician is verifying the operational characteristics of an IEEE 802.1Q trunk link established between two Cisco Catalyst switches. Which two statements describe correct behavior or features of IEEE 802.1Q trunking? (Select two.)
- Frames belonging to the configured native VLAN are transmitted across the trunk link untagged by default.Answer
- BA native VLAN mismatch across a trunk link causes both switch interfaces to immediately enter an err-disabled state.
- IEEE 802.1Q inserts a 4-byte header into the standard Ethernet frame to carry VLAN identification information.Answer
- DSpanning Tree PortFast should be enabled on interswitch trunk ports to minimize VLAN convergence times.
Answer
The correct statements are that native VLAN frames are transmitted untagged across an 802.1Q trunk by default, and that IEEE 802.1Q inserts a 4-byte header into the Ethernet frame.
IEEE 802.1Q trunking inserts a 4-byte tag between the MAC Source Address and EtherType fields of an Ethernet frame for tagged VLAN traffic. By default, frames originating from or destined for the native VLAN are sent across the trunk link without any 802.1Q tag attached.
Step-by-Step Solution
Key Concept
IEEE 802.1Q Trunking Fundamentals and Native VLAN Mechanics