Which of the following statements regarding scheduling on the Alcatel-Lucent 7750 SR is TRUE? (Choose two)

Question

Options

• AWhen using profile-mode queues, traffic that is marked as in-profile on ingress and scheduled in
• BWhen an HQoS strategy using an egress port-scheduler has been deployed, Tier 1 receives its
• CThe greater the difference between PIR and CIR rates in a queue, the less likely a CIR will be
• DPackets scheduled out of high-priority queues in the default scheduler will have a lower chance of
• EWhen using priority-mode queues, traffic that is marked as in-profile on ingress and scheduled in

• A
  94% (49)
• B
  2% (1)
• E
  4% (2)

Explanation

Options A and C are correct because they accurately describe 7750 SR scheduling behavior: in profile-mode queues, traffic colored as in-profile at ingress retains that profile designation through egress scheduling, giving it preferential treatment and reducing discard probability. For option C, when the PIR-CIR gap is large, the scheduler can push significantly more out-of-profile traffic alongside committed traffic - during congestion, this excess burst capacity makes it harder for the scheduler to reliably honor the CIR, effectively reducing the likelihood that the committed rate guarantee holds.

Option B is wrong because Tier 1 in an HQoS port-scheduler does not receive priority in the way the statement implies - port-scheduler tiers follow specific scheduling rules where higher tiers don't simply dominate lower ones unconditionally.

Option D is wrong because it reverses the correct behavior: packets from high-priority queues in the default scheduler have a higher (not lower) probability of being transmitted before lower-priority traffic.

Option E is wrong because priority-mode queues schedule based on queue priority alone, not ingress color marking - unlike profile-mode, in-profile coloring from ingress does not carry forward to influence egress scheduling behavior.

Memory tip: Think "Profile-mode = color carries through" vs. "Priority-mode = priority only." For C, use the analogy of a highway lane: the bigger the PIR-CIR gap, the more cars can merge into your committed lane, crowding out your guarantee.

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