200-301 Question 188
Select 3Two switches, SwitchA and SwitchB, are connected via their GigabitEthernet0/1 interfaces. After configuring the link, the network administrator notices that VLAN traffic is not passing between the switches. Upon inspecting the configuration, they observe that the trunk link is not operational. Which of the following actions should the administrator take to resolve the issue?
- A
Ensure the native VLAN is the same on both switches.
- B
Configure the link as a trunk using the 'switchport mode trunk' command.
- C
Manually assign allowed VLANs to the trunk using the 'switchport trunk allowed vlan' command.
- D
Enable Dynamic Trunking Protocol (DTP) on both switches with the 'switchport mode dynamic desirable' command.
- E
Verify that both interfaces are in the 'up/up' state using the 'show interfaces status' command.
Show answer and explanation
Correct answers: A, B, E
Explanation
To establish interswitch connectivity over a trunk link, the trunk mode must be configured, the native VLAN must match, and the physical link must be operational. These steps ensure proper VLAN tagging and forwarding between the switches. Optional configurations like VLAN filtering can be applied later but are not required for the trunk to initially function.
- A. Correct.
Ensuring the native VLAN matches on both switches is critical because mismatched native VLANs can cause traffic to be dropped or misinterpreted.
- B. Correct.
Manually configuring the interfaces as a trunk ensures that the link operates in trunk mode, especially if DTP is disabled or not supported.
- C. Incorrect.
Assigning VLANs to the trunk is not necessary to establish the trunk link initially; this step is optional for further VLAN filtering or restrictions.
- D. Incorrect.
Enabling DTP is unnecessary if the trunk mode is manually configured, and not all environments use DTP due to potential security concerns.
- E. Correct.
Verifying the interface state ensures that physical connectivity issues are ruled out.