Shape Outbound and Police Inbound to Protect a 10 Mbps Link

300-420 By islever Editorial Last updated

Design end-to-end QoS policies

Short answer

C Shape outbound to smooth egress within the 10 Mbps link, and police inbound to cap received traffic so business-critical flows are not starved.

Question

An engineer is designing a QoS solution for a customer. The customer's internet connection has a bandwidth of 10 Mbps. The design must ensure that traffic bursts of data do not exceed the bandwidth of the connection and that received traffic does not starve out business-critical traffic. Which solution must the engineer choose?
  1. Configure the queuing default queue for shaping inbound and policing inbound.
  2. Configure the queuing default queue for shaping inbound and policing outbound.
  3. Configure the queuing default queue for shaping outbound and policing inbound. Correct Answer
  4. Configure the queuing default queue for shaping outbound and policing outbound.

Key Takeaways

Shaping is an egress (outbound) tool; policing is an ingress (inbound) tool. Match each to its direction: shape outbound, police inbound.

On a small 10 Mbps internet handoff, traffic shaping is applied outbound to smooth egress toward the provider so bursts stay within the link bandwidth, while policing is applied inbound to cap received traffic and protect business-critical flows from starvation.

Common mistake: Picking A or B (shaping inbound): you cannot shape traffic you receive — shaping smooths what you send, so it is always outbound; policing limits what arrives, so it is inbound.

Expert Analysis

Why the Answer Is Correct

C is correct. Shaping is applied outbound on the handoff to the provider: it smooths egress so traffic bursts never exceed the 10 Mbps circuit. Policing is applied inbound to cap received traffic and ensure business-critical flows are not starved by best-effort traffic.

Why the Other Options Are Wrong

A and B put shaping inbound, which is impossible — you shape what you transmit, not what you receive. D polices outbound, but policing protects the inbound side where received traffic could starve critical flows.

Community Comment Notes

The vote is C (75) vs B (25). Commenters cite the QoS texts: shaping smooths outbound traffic toward the provider, policing limits inbound traffic, and critical traffic is elevated to a higher class.

Exam Strategy

Distinguish between shaping and policing by their direction: shaping is always outbound (egress) to smooth bursts, while policing is typically inbound (ingress) to drop excess. Look for keywords like 'burst' pointing to shaping and 'starve' or 'limit incoming' pointing to policing.

Frequently Asked Questions

Why must shaping be applied outbound in QoS design?

Shaping controls the rate of traffic you transmit to match circuit capacity, smoothing bursts toward the provider.

How does policing protect critical traffic from starvation?

Policing inbound traffic caps incoming rates, preventing non-critical flows from overwhelming buffers and starving business-critical packets.

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Community Votes

C
75%
B
25%

75% of anonymous learners picked answer C. Votes are pick records left by other test-takers — they are not the verified answer.

Discussion 5 contributions

Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.

From public community threads 5

  1. Aaron_0801 👍 1 Answered C
    Provided answer is correct. From the book: "In enterprise environments, traffic shaping is used to smooth the flow of traffic going out to the provider." "Generally, policing is used to set the limit of traffic coming into an interface (ingress)" and "One example of using policing is giving preferential treatment to critical application traffic by elevating to a higher class and reducing best-effort traffic to a lower-priority class."
  2. neiker45 👍 1
    You always want to shape traffic outbound unless it is a very specific case.
  3. rickyarchi 👍 2 Answered C
    Shaping is only used outbound
  4. ajinkya_gooner 👍 1
    This should be D
  5. RexChen 👍 1 Answered B
    should be B

Reader comments & corrections

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