Layer 2 Traffic Tunneling (Q-in-Q, L2PT) JN0-650 Practice Questions (Page 3)

Questions 11–15

1. 11foundation · easy

   In a Q-in-Q tunneling scenario, which VLAN tag is used by the service provider to forward frames across its backbone?

   • ABoth tags are used equally for forwarding decisions
   • BThe provider uses the MAC address only, ignoring VLAN tags
   • CThe outer service-provider VLAN tag
   • DThe inner customer VLAN tag
   Reveal Solution Discussion Select an answer first
2. 12application · medium

   A customer reports that their Q-in-Q service is not passing traffic between two sites. The provider edge interfaces are configured with flexible-vlan-tagging and the correct outer/inner tags. However, the provider core switches are not forwarding the double-tagged frames. What is the most likely cause?

   • AThe core switches do not have the outer VLAN (e.g., VLAN 100) allowed on their trunk interfaces.
   • BThe core switches are configured with vlan-tagging instead of flexible-vlan-tagging.
   • CThe customer's inner VLAN ID is not unique across the provider network.
   • DThe edge interfaces are using the default MTU, which is too small for double-tagged frames.
   Reveal Solution Discussion Select an answer first
4. 13expert · medium

   A service provider is designing a Q-in-Q service for a customer that requires transparent transport of their VLANs. The customer has two sites, each with multiple VLANs. The provider wants to minimize the number of outer tags used while ensuring isolation between customers. Which approach best meets these requirements?

   • AAssign a unique outer tag for each customer VLAN.
   • BUse QinQ only on the edge and use MPLS in the core to carry customer VLANs.
   • CAssign a single outer tag per customer and use the inner tag to distinguish VLANs.
   • DUse the same outer tag for all customers and rely on the inner tag for separation.
   Reveal Solution Discussion Select an answer first
5. 14expert · hard

   A service provider is troubleshooting an issue where customer STP BPDUs are not being tunneled across the network, even though L2PT is configured on the edge interfaces. The provider also runs its own STP. The customer's BPDUs are being processed by the provider's STP, causing topology changes. What is the most likely cause?

   • AThe edge interfaces are configured with vlan-tagging instead of flexible-vlan-tagging.
   • BThe customer's BPDUs are being sent with a multicast MAC address that is not recognized by L2PT.
   • CL2PT is not enabled for the STP protocol on the egress interface.
   • DThe provider's STP priority is lower than the customer's, causing the provider to become root.
   Reveal Solution Discussion Select an answer first
6. 15foundation · easy

   Which symptom indicates a possible L2PT configuration failure?

   • ACustomer LLDP frames are being dropped
   • BCustomer data frames are being encrypted
   • CProvider switches are learning customer MAC addresses
   • DCustomer STP BPDUs are being processed by the provider's switches, causing loops
   Reveal Solution Discussion Select an answer first