GCIA · Question #84
You work as a Network Administrator for Tech Perfect Inc. The company has a TCP/IP-based network. A branch office is connected to the headquarters through a T1 line. Users at the branch office report
The correct answer is D. Configure traffic shaping to reduce bandwidth for WorkReport.. When a bulk-transfer application monopolizes a shared WAN link and degrades VoIP quality, the correct QoS remedy is to apply traffic shaping to reduce bandwidth for that application, freeing capacity for latency-sensitive voice traffic.
Question
You work as a Network Administrator for Tech Perfect Inc. The company has a TCP/IP-based network. A branch office is connected to the headquarters through a T1 line. Users at the branch office report poor voice quality on the IP phone while communicating with the headquarters. You find that an application, named WorkReport, at the branch office is suffocating bandwidth by sending large packets for file synchronization. You need to improve the voice quality on the IP phone. Which of the following steps will you choose to accomplish this?
Options
- AConfigure traffic shaping to increase the time interval for the WorkReport packets.
- BConfigure traffic shaping to increase the time interval for the IP phone packets.
- CConfigure traffic shaping to reduce bandwidth for the IP phone.
- DConfigure traffic shaping to reduce bandwidth for WorkReport.
How the community answered
(33 responses)- A9% (3)
- B3% (1)
- C3% (1)
- D85% (28)
Why each option
When a bulk-transfer application monopolizes a shared WAN link and degrades VoIP quality, the correct QoS remedy is to apply traffic shaping to reduce bandwidth for that application, freeing capacity for latency-sensitive voice traffic.
Increasing the time interval for WorkReport packets slightly spreads out bursts but does not place a hard cap on its bandwidth consumption, so the T1 link can still be saturated between intervals.
Increasing the time interval for IP phone packets would introduce additional jitter and delay into the voice stream, degrading call quality rather than improving it.
Reducing bandwidth for the IP phone restricts the very application that needs priority treatment, which would make voice quality worse, not better.
Configuring traffic shaping to reduce the bandwidth available to WorkReport directly throttles the large file-synchronization packets that are consuming the T1 link, leaving sufficient headroom for the low-latency, low-jitter requirements of IP voice traffic and improving call quality.
Concept tested: QoS traffic shaping to prioritize VoIP over bulk data
Source: https://www.cisco.com/c/en/us/support/docs/quality-of-service-qos/qos-policing/19645-qos-traffic-shaping.html
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