CCDE: Cisco Certified Design Expert (Written) — Question 54

You are the lead network designer hired by Service Provider XYZ to deploy CoS functionality on the core MPLS network (P routers). The goal of the network design is to provide a complete CoS solution to all customers that purchase services such as dedicated internet access, MPLS L3VPN, and L2VPN (pseudowire).
Service Provider XYZ has these design requirements:
- The network supports four service queues with equal treatment for delay, jitter, and packet loss.
- Queues are numbered 0-3, where 0 is the default queue.
- Three queues have one treatment.
- One queue has either one or two treatments.
How would you design your solution to map the DSCP value properly so that the traffic is assigned to the respective queues in the Service Provider XYZ MPLS core network?

Answer options

• A. Classify traffic according to DSCP value into appropriate P router queues.
• B. Map the appropriate DSCP value into the EXP field based on the number of queues in the MPLS P routers.
• C. Map the appropriate DSCP value into the EXP field based on the number of queues in the MPLS PE routers.
• D. Based on the DSCP value, traffic is mapped automatically into appropriate queues in the MPLS CE routers.

Correct answer: C

Explanation

The correct answer is C because mapping the DSCP value to the EXP field in the MPLS PE routers ensures proper prioritization of traffic within the MPLS architecture. Options A and D are incorrect as they focus on P and CE routers respectively, which do not handle the DSCP to EXP mapping for the core MPLS network. Option B is also incorrect because the P routers do not perform the same mapping function as the PE routers in this context.