Designing Cisco Enterprise Networks (ENSLD) — Question 73

An engineer must design a QoS solution for a customer that is connected to an ISP over a 1Gbps link with a 100Mbps CIR. The ISP aggressively drops all traffic received over the CIR, which is causing numerous TCP retransmissions. The customer is not using any RTP applications but wants to maximize bandwidth usage up to the CIR. Which QoS solution should the engineer choose?

Answer options

• A. policing
• B. queuing
• C. traffic shaping
• D. policer with markdown

Correct answer: C

Explanation

Traffic shaping is the correct solution as it allows for the regulation of traffic flow to match the 100Mbps CIR, thus preventing excessive drops that lead to TCP retransmissions. Policing, while it can limit traffic, would drop packets once the CIR is exceeded, worsening the situation. Queuing does not directly address the need to control the traffic rate, and the policer with markdown option is not appropriate for this scenario.