Which of the following statements BEST describes an MBS parameter?

Question

Options

• AIt specifies the maximum rate at which a queue can be serviced.
• BIt specifies the maximum depth of a queue beyond which packets will be dropped.
• CIt specifies the portion of a queue that is taken from the reserved buffer pool.
• DIt specifies the threshold beyond which only in-profile packets will be queued.
• EIt specifies the peak bandwidth that can be attained by the incoming traffic.

• A
  3% (1)
• B
  93% (27)
• C
  3% (1)

Explanation

MBS (Maximum Buffer Size) defines the absolute ceiling on how deep a queue can grow - once the queue reaches this depth, any additional arriving packets are tail-dropped, making B correct.

Why the distractors are wrong:

• A describes a scheduler or PIR (Peak Information Rate) concept, which controls service rate, not buffer depth.
• C describes the CBS (Committed Burst Size) parameter, which controls how much of the reserved buffer pool a queue can use before dipping into shared buffers.
• D describes a High Priority Only (HPO) threshold, where the queue accepts only high-priority (in-profile) traffic once that threshold is crossed.
• E describes PIR (Peak Information Rate), which caps the bandwidth of incoming or outgoing traffic, not the queue storage.

Memory tip: Think of MBS = Maximum Bucket Size - picture a physical bucket collecting water (packets); MBS is the rim of the bucket. Once water hits the rim, the overflow (excess packets) spills away and is dropped.

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