What Is the BFD Multiplier in Application-Aware Routing?
What is the BFD multiplier in application-aware routing?
Community Votes
70% of anonymous learners picked answer A. Votes are pick records left by other test-takers — they are not the verified answer.
Community Insight
The question tests the AAR SLA-classification multiplier (default 6), not the tunnel-liveness BFD multiplier (default 7) that most candidates memorize first.
In Cisco SD-WAN application-aware routing (AAR), the BFD multiplier sets how many poll intervals are averaged to compute mean loss, latency and jitter, and its default value is 6. This page establishes that option A is correct and explains why the familiar tunnel BFD multiplier of 7 does not answer this question.
Picking 7 because it is the widely cited default BFD multiplier for SD-WAN tunnel liveness (hello-interval 1000 ms, multiplier 7, DSCP 48) — but the AAR multiplier that averages poll intervals for SLA classification defaults to 6.
Community Discussion (8 comments)
Comments & Corrections
No comments yet — spotted an error or have a note? Share it below.
Expert Analysis
Why the Answer Is Correct
In Cisco SD-WAN application-aware routing, each tunnel carries BFD probes whose poll intervals capture loss, latency and jitter. AAR then classifies the tunnel's SLA using the last N poll intervals, where N is the BFD multiplier — a user-configurable parameter in the AAR profile. The Cisco default for that multiplier is 6, so the SLA verdict is derived from the six most recent poll intervals. Option A (6) is therefore the correct value. This matches what iking describes on the page: "The default value for the BFD multiplier in application-aware routing is 6."
Why the Other Options Are Wrong
Option B (7) is the real-world trap: it is the default BFD multiplier for tunnel liveness on Cisco SD-WAN devices, cited alongside hello-interval 1000 ms and DSCP 48, but it is not the AAR SLA multiplier. As jstaruch put it, "with AAR it is different from the default BFD multiplier by normal SDWAN tunnel," and Networkchamp87's own quote about probes being lost before a tunnel is declared down describes liveness detection, not SLA averaging. Options C (8) and D (9) are pure distractors — neither value is a Cisco default for any SD-WAN BFD multiplier, and no commenter or Cisco document endorses them.
Community Comment Notes
The anonymous vote distribution (70 for A, 30 for B) is not proof on its own, but it aligns with the AAR documentation: the 6-multiplier value is the one exposed in the vManage AAR profile and reflected in the SLA-classification explanation that "the information from all the poll intervals (specifically, from the last six poll intervals) is used to determine the classification." The B-voters, including hamidreza0010 and Stanleymahamadi's later reply, are repeating the generic SD-WAN BFD liveness values rather than the AAR multiplier. Read the question's qualifier carefully — "in application-aware routing" is doing all the work here.
Official Reference
Exam Strategy
Anchor on the qualifier phrase: if the stem says "application-aware routing," think SLA classification and the default multiplier of 6; if it says tunnel, liveness or hello-interval, think the multiplier of 7. Memorize the pair (AAR = 6 for poll-interval averaging, tunnel BFD = 7 for declaring a tunnel down) so the distractor cannot flip your answer.
Frequently Asked Questions
Why is the AAR BFD multiplier 6 and not 7?
Six is the default multiplier that averages the last six poll intervals for AAR SLA classification; seven is the separate default multiplier used for tunnel liveness detection.
What does the AAR multiplier actually control?
It multiplies the poll interval to define how far back AAR looks when calculating mean loss, mean latency and mean jitter for the tunnel.
Related Analysis
Practice All 300-415 Questions
Access 120 questions with complete answers and detailed explanations.
View Full 300-415 Practice Test →