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Zorluk: OrtaQoS Per-Hop Behaviors, Classification, Marking, Queuing, and Traffic Shaping/Policing

A network administrator is troubleshooting TCP application performance degradation on an enterprise egress WAN interface. Analysis shows that momentary traffic spikes above the contracted service rate are causing immediate packet drops, leading to TCP global synchronization and reduced throughput. Which QoS modification should be applied to the WAN interface to smooth out traffic bursts by delaying excess packets in a buffer rather than dropping them immediately?

  1. Apply a traffic shaping policy on the egress interface to queue and smooth out excess bursts.Cevap
  2. B
    Apply a traffic policing policy on the egress interface to buffer out-of-profile packets until the next time interval.
  3. C
    Configure Class-Based Header Compression to shrink packet headers during traffic bursts.
  4. D
    Enable ingress traffic policing on the WAN router interface to hold burst packets until interface utilization drops.

Cevap

Apply a traffic shaping policy on the egress interface to queue and smooth out excess bursts.
Traffic shaping regulates egress network traffic by holding excess packets in a buffer queue when traffic bursts exceed the configured Committed Information Rate (CIR). It then releases those packets smoothly over time, preventing packet drops and avoiding TCP global synchronization.

Adım Adım Çözüm

1
Identify the cause of TCP global synchronization.
Immediate dropping of bursty packets by hard rate enforcement causes multiple TCP senders to slow down simultaneously.
When bursts exceed the rate limit and packets are discarded immediately, TCP sessions experience tail drop and enter slow start.
2
Compare traffic conditioning mechanisms (policing vs. shaping).
Policing discards or remarks non-conforming traffic without buffering. Shaping uses a software buffer to store excess packets and schedule them for later transmission.
To smooth bursts without dropping packets, a buffering mechanism (traffic shaping) is required.
3
Select the correct QoS policy implementation.
Configuring egress traffic shaping buffers out-of-profile traffic during short spikes and transmits it as rate tokens become available.
Traffic shaping is designed specifically for egress interface smoothing using packet queues.

Anahtar Kavram

Differences in operational mechanics between Traffic Shaping (buffering/smoothing) and Traffic Policing (dropping/remarking)
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Konular

QoS Per-Hop Behaviors, Classification, Marking, Queuing, and Traffic Shaping/Policing

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