200-301 Question 171
Single answerYou are tasked with configuring VLAN 20 on two switches (SW1 and SW2) and ensuring that devices in VLAN 20 can communicate across both switches. After creating VLAN 20 on both switches, you configure the access ports and assign them to VLAN 20. However, devices in VLAN 20 on SW1 cannot communicate with devices in VLAN 20 on SW2. Which additional step must you take to resolve this issue?
- A
Configure a trunk port between SW1 and SW2 and allow VLAN 20 on the trunk link.
- B
Enable Spanning Tree Protocol (STP) to manage VLAN 20 traffic between the switches.
- C
Assign an IP address to VLAN 20 on both switches.
- D
Configure a Layer 3 router to route traffic between the switches.
Show answer and explanation
Correct answer: A
Explanation
In a multi-switch environment, VLANs need to be carried across switches using trunk ports. Trunk ports allow multiple VLANs to traverse a single physical link between switches by tagging frames with VLAN IDs. Without a trunk port configured between SW1 and SW2, VLAN 20 traffic will remain isolated on each switch, preventing communication between devices in VLAN 20 across the switches. Therefore, configuring a trunk port and allowing VLAN 20 on the trunk link resolves the issue.
- A. Correct.
Correct. To allow VLAN 20 traffic to pass between SW1 and SW2, you must configure a trunk port between them and ensure VLAN 20 is allowed on the trunk link.
- B. Incorrect.
Incorrect. While STP prevents loops in a switched network, it does not enable VLAN traffic to traverse switches. You need a trunk port to handle inter-switch VLAN traffic.
- C. Incorrect.
Incorrect. Assigning an IP address to VLAN 20 is only necessary for inter-VLAN routing or management purposes. It does not resolve the issue of VLAN 20 communication between switches.
- D. Incorrect.
Incorrect. A Layer 3 router is not required for communication within the same VLAN across switches. A properly configured trunk link is sufficient.