Your customer requests that you provide a transparent Layer 2 service between two of their remote locations. This service must allow them to pass tagged traffic from multiple VLANs. You decide to use Q-in-Q tunneling on the two provider edge MX Series routers that connect to the customers CE devices.
Which two statements are true? (Choose two.)
Click on the arrows to vote for the correct answer
A. B. C. D.BC
The scenario requires transparent Layer 2 service, where the service provider network should allow the customer to pass tagged traffic from multiple VLANs. In such cases, Q-in-Q tunneling can be used to transport multiple VLANs over a single VLAN.
Q-in-Q tunneling is a technique that encapsulates an Ethernet frame within another Ethernet frame. The outer VLAN tag is used to identify the customer VLAN, while the inner VLAN tag is used to identify the specific VLAN within the customer network.
Now, let's go through each option to see which are true:
A. The CE-facing interfaces on the PE devices must be configured as trunk ports. This statement is true. As Q-in-Q tunneling is used to transport multiple VLANs over a single VLAN, the customer-facing interfaces on the PE devices must be configured as trunk ports to allow multiple VLANs to pass through.
B. The CE-facing interfaces on the PE devices must be configured as access ports. This statement is false. Access ports are used to connect end devices that do not support VLAN tagging. In this scenario, the customer devices support VLAN tagging, so the CE-facing interfaces on the PE devices must be configured as trunk ports.
C. The PE-facing interfaces on the CE devices must be configured as trunk ports. This statement is false. The PE-facing interfaces on the CE devices should be configured as access ports because the provider network does not need to know about the customer's VLANs. The provider network only needs to transport the tagged traffic received from the CE device across the provider network to the other CE device.
D. The PE-facing interfaces on the CE devices must be configured as access ports. This statement is true. The PE-facing interfaces on the CE devices must be configured as access ports to receive the Q-in-Q tagged traffic from the provider network. As the provider network is encapsulating the customer VLANs within its own VLAN, the CE devices do not need to be aware of the customer VLANs. Hence, the PE-facing interfaces on the CE devices must be configured as access ports.
In summary, options A and D are the correct answers. The CE-facing interfaces on the PE devices must be configured as trunk ports, and the PE-facing interfaces on the CE devices must be configured as access ports to allow the Q-in-Q tunneling to work correctly.