Which SLA metric is most likely triggering a failover policy when voice traffic is intermittently rerouted from MPLS to broadband despite acceptable latency values?

• A. OSPF dead timer expiration
• B. CAPWAP retransmission
• C. Packet loss threshold violation
• D. STP topology change

Answer: (C)

When evaluating how SD-WAN decides to fail over a WAN path, the key driver is the quality of the ongoing connection measured by SLA metrics such as packet loss, jitter, and latency. Voice traffic is extremely sensitive to packet loss; even if latency stays within acceptable bounds, a rise in lost packets on the active MPLS path will quickly degrade voice quality. Therefore, the failover policy will switch to the backup broadband link to maintain call quality as soon as the packet loss crosses its configured threshold. The other options don’t fit this scenario: OSPF dead timer relates to routing neighbor stability rather than per-traffic SLA metrics; CAPWAP retransmission points to wireless AP-controller tunnels; and an STP topology change concerns Layer 2 path changes, not SLA-based WAN path selection for voice.