SD-WAN TLOC Selection with SLA and Application-Aware Routing

Q: Does SLA determine the path if both links meet it?

SLA acts as a filter. If both meet SLA and no preferred color is set, the path with the best underlying metrics (latency/loss) is chosen.

Q: Why not load balance between MPLS and Internet?

Without explicit ECMP configuration, SD-WAN selects a single best active path based on policy and metrics, not load balancing.

300-415 By islever Editorial Last updated Sep 27, 2026

Short answer

A The MPLS TLOC is selected because it offers superior latency and loss metrics compared to the Internet TLOC while satisfying all SLA thresholds.

Question

Refer to the exhibit. A WAN Edge router is configured with SLAs. Which TLOC does the traffic take if the internet TLOC has latency 100 ms, loss 2%, jitter 50ms, and the MPLS TLOC has latency 50 ms, loss 1%, and jitter 150 ms? - Exhibit: SD-WAN TLOC Selection with SLA and Application-Aware Routing

Exhibit: SD-WAN TLOC Selection with SLA and Application-Aware Routing

MPLS Correct Answer
internet
MPLS or internet
drop

Key Takeaways

Tests the interaction between SLA compliance and metric-based selection when a specific preferred color is absent from the policy.

Determines the correct TLOC path when SLA thresholds are met by both options but no preferred color is configured, relying on application-aware routing metrics.

Common mistake: Choosing 'MPLS or internet' because both links meet the SLA requirements, ignoring that SD-WAN must select a single active path for forwarding based on best available metrics.

Expert Analysis

Why the Answer Is Correct

The traffic takes the MPLS TLOC because both interfaces satisfy the defined SLA thresholds (Latency <100ms, Loss <5%, Jitter <200ms). When an Application-Aware Routing (AAR) policy does not specify a 'preferred_color', the SD-WAN controller selects the best available path based on the lowest cost/metric among compliant paths. Since MPLS has superior latency (50ms vs 100ms) and significantly lower loss (1% vs 2%), it is selected as the primary path.

Why the Other Options Are Wrong

Option B (Internet) is incorrect because while it meets the SLA, it has higher latency and loss compared to MPLS, making it the inferior choice when no preference is forced. Option C (MPLS or internet) is incorrect because SD-WAN forwards traffic over a single active TLOC per flow/session; it does not load balance across multiple underlay paths unless explicitly configured with ECMP policies, which is not indicated here. Option D (Drop) is incorrect because the traffic is compliant with the SLA class actions.

Community Comment Notes

Commenter Traktark notes that MPLS is chosen because jitter constraints were not the deciding factor in this specific scenario, highlighting that all metrics matter. Another user argues for both paths being valid, citing Cisco Press documentation about configurations where no preferred color is set, implying equal treatment, but fails to account for the tie-breaking mechanism of underlying transport metrics. A third commenter correctly identifies that while SLA is relevant for eligibility, the final selection relies on the better metrics (latency/loss) when SLA is merely a pass/fail gate.

Exam Strategy

Always check if a 'preferred_color' is specified in the AAR policy. If yes, that color wins regardless of metrics (as long as SLA is met). If no preferred color is specified, choose the link with the best transport metrics (lowest latency/loss/jitter) among those meeting SLA.

Frequently Asked Questions

Does SLA determine the path if both links meet it?

SLA acts as a filter. If both meet SLA and no preferred color is set, the path with the best underlying metrics (latency/loss) is chosen.

Why not load balance between MPLS and Internet?

Without explicit ECMP configuration, SD-WAN selects a single best active path based on policy and metrics, not load balancing.

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Community Votes

75%

25%

75% of anonymous learners picked answer A. Votes are pick records left by other test-takers — they are not the verified answer.

Discussion 3 contributions

Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.

From public community threads 3

Traktark 👍 2 Answered A

A - MPLS, because jitter is not set up in policy
34b33cd 👍 1 Answered C

I agree with mikidvd51. Both MPLS and Internet are within the defined SLA class and both are compliant. In that case, traffic can traverse through both MPLS and Internet based on the principles of application aware routing. Following snippet is from Cisco Press Book "Another variation of this configuration is where the SLA Class action is specified but no preferred color is specified. In this case, the traffic is load-shared per flow among all of the colors that meet the required SLA."
domac385 👍 1 Answered A

As this is Application-aware routing policy, SLA is irrelevant for this as both TLOCs are within SLA defined. But MPLS has better metrics so it will be preffered over Internet.

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