A network technician connects two switches, Switch-A and Switch-B, via an 802.1Q trunk link. Users on VLAN 10 connected to Switch-A cannot communicate with users on VLAN 10 attached to Switch-B. Console output on Switch-A displays `%CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on interface GigabitEthernet0/1 (10), with Switch-B GigabitEthernet0/1 (1)`. Which TWO of the following statements correctly explain the network behavior and the required resolution?
- Untagged frames sent by Switch-A on native VLAN 10 are received by Switch-B and assigned to VLAN 1.Answer
- Configuring the native VLAN to match on both ends of the trunk interface will resolve the connectivity issue.Answer
- CThe native VLAN mismatch causes late collisions on GigabitEthernet0/1, requiring both switch interfaces to be explicitly set to half-duplex.
- DOnce the native VLAN mismatch is cleared, hosts on VLAN 10 and VLAN 1 will be able to communicate directly without a Layer 3 router.
Answer
The two correct statements are that untagged frames sent by Switch-A on native VLAN 10 are received by Switch-B and assigned to VLAN 1, and configuring the native VLAN to match on both ends of the trunk interface will resolve the connectivity issue.
Under the IEEE 802.1Q standard, traffic on the native VLAN travels untagged across trunk links. When Switch-A uses VLAN 10 as native and Switch-B uses VLAN 1, untagged frames sent from Switch-A's VLAN 10 arrive at Switch-B and are incorrectly processed as VLAN 1 frames. Reconfiguring both switch interfaces to share the same native VLAN restores proper frame segregation and trunk connectivity.
Step-by-Step Solution
Key Concept
802.1Q Trunk Native VLAN Mismatch Identification and Resolution