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300-415 · Question #366

A customer requires reliability for voice traffic and has MPLS, biz-Internet, and public-Internet transports. Which control policy configuration maintains a better SLA and avoids blackholing of…

The correct answer is B. Policy configuration starting with 'policy sla-class VOICE_TRAFFIC latency 50 loss 5' and specifying `preferred-color mpls` with `backup-sla-preferred-color biz-internet`. This question asks to identify the best control policy configuration for voice traffic, prioritizing MPLS with a backup, to ensure reliability and avoid blackholing.

Policies

Question

A customer requires reliability for voice traffic and has MPLS, biz-Internet, and public-Internet transports. Which control policy configuration maintains a better SLA and avoids blackholing of voice traffic?

Exhibit

300-415 question #366 exhibit

Options

  • APolicy configuration starting with 'policy sla-class VOICE_TRAFFIC latency 0' and specifying preferred-color mpls.
  • BPolicy configuration starting with 'policy sla-class VOICE_TRAFFIC latency 50 loss 5' and specifying preferred-color mpls with backup-sla-preferred-color biz-internet.
  • CPolicy configuration starting with 'policy sla-class VOICE_TRAFFIC latency 150 loss 5' and specifying preferred-color mpls with backup-sla-preferred-color biz-internet.
  • DPolicy configuration starting with 'policy sla-class VOICE_TRAFFIC latency 150 loss 5' and specifying preferred-color mpls (no backup color shown).

How the community answered

(41 responses)
  • A
    2% (1)
  • B
    78% (32)
  • C
    5% (2)
  • D
    15% (6)

Why each option

This question asks to identify the best control policy configuration for voice traffic, prioritizing MPLS with a backup, to ensure reliability and avoid blackholing.

APolicy configuration starting with 'policy sla-class VOICE_TRAFFIC latency 0' and specifying `preferred-color mpls`.

A latency of `0` is an unrealistic and unachievable SLA requirement, making this policy ineffective or constantly failing. It also lacks a backup SLA preferred color, risking blackholing.

BPolicy configuration starting with 'policy sla-class VOICE_TRAFFIC latency 50 loss 5' and specifying `preferred-color mpls` with `backup-sla-preferred-color biz-internet`.Correct

This policy defines an SLA class for voice traffic with reasonable latency (50 ms) and loss (5%) thresholds, which are typical for real-time voice applications. It then specifies `preferred-color mpls` to prioritize the high-quality MPLS link and includes `backup-sla-preferred-color biz-internet` to ensure that if MPLS fails or degrades below SLA, traffic can seamlessly switch to the business internet link, preventing blackholing and maintaining service.

CPolicy configuration starting with 'policy sla-class VOICE_TRAFFIC latency 150 loss 5' and specifying `preferred-color mpls` with `backup-sla-preferred-color biz-internet`.

A latency of `150` ms is generally too high for real-time voice traffic, which typically requires much lower latency for good quality, making this SLA less suitable for voice.

DPolicy configuration starting with 'policy sla-class VOICE_TRAFFIC latency 150 loss 5' and specifying `preferred-color mpls` (no backup color shown).

A latency of `150` ms is too high for voice traffic, similar to C. Additionally, it lacks a `backup-sla-preferred-color`, which is crucial for reliability and avoiding blackholing when the primary preferred color fails or degrades.

Concept tested: SLA class configuration for voice traffic with preferred and backup colors

Source: https://www.cisco.com/c/en/us/td/docs/routers/sdwan/configuration/policies/ios-xe-17/sdwan-policies-book-xe/application-aware-policies.html

Topics

#SD-WAN Policies#SLA Class#Voice QoS#Path Selection

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