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 which is causing numerous…

Question

Options

• APolicing
• BTraffic shaping
• CPolicer with markdown
• DQueuing

• A
  4% (2)
• B
  80% (45)
• C
  5% (3)
• D
  11% (6)

Explanation

Traffic Shaping is the correct solution. The problem is that the ISP aggressively drops all traffic exceeding the 100Mbps CIR on the 1Gbps link, causing TCP retransmissions and reduced throughput. Traffic shaping buffers (queues) excess traffic when the output rate would exceed the CIR, then releases it in a smooth, metered flow at or below the CIR. This prevents packets from being dropped by the ISP, eliminates unnecessary TCP retransmissions, and maximizes effective bandwidth utilization up to the CIR. Since the customer has no RTP (real-time) applications, the added delay from shaping buffers is acceptable. Policing (A) would drop or remark traffic above the CIR on the customer side, but dropped TCP packets still cause retransmissions, reducing throughput rather than maximizing it. A policer with markdown (C) marks down excess traffic, but the ISP still drops it aggressively, so TCP retransmissions persist. Queuing (D) prioritizes traffic but does not rate-limit output to the CIR, so the ISP continues to drop excess traffic.

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