Which of the following statements BEST describes where shaping mechanisms should be applied?

Question

Options

• AOn all ports on the Alcatel-Lucent 7750 SR.
• BAt the junction of high-speed to low-speed links or at places of traffic aggregation.
• CAt the junction of low-speed to high-speed links or at places of traffic aggregation.
• DOn low-speed WAN links.
• ENowhere. Shaping is only performed in hardware and serviced in a round-robin.

• A
  3% (1)
• B
  77% (27)
• C
  14% (5)
• D
  6% (2)

Explanation

Option B is correct because shaping is designed to smooth traffic bursts and enforce rate limits before traffic hits a bottleneck - specifically where a high-speed link feeds into a slower one (to avoid downstream congestion/drops) or where multiple flows aggregate (to control the combined output rate).

Why the distractors fail:

• A is wrong because applying shaping on all ports is wasteful and unnecessary - it adds overhead where no speed mismatch or aggregation problem exists.
• C reverses the logic: going from low-speed to high-speed, the faster link absorbs traffic easily, so shaping there would only artificially throttle throughput for no benefit.
• D is too narrow - shaping is applied at the egress toward a low-speed WAN link, not universally on all low-speed links, and the concept extends beyond WAN to any aggregation point.
• E is entirely false; shaping is a deliberate, configurable QoS function, not absent by design.

Memory tip: Think "fast-to-slow = shape the flow." Picture water rushing from a wide pipe into a narrow one - you need a valve (shaper) at that junction to prevent overflow, not on the narrow pipe itself or on the wide side going to an even wider pipe.

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