In cisco SD_WAN, which protocol is used to measure link quality?

Question

Options

• AOMP
• BBFD
• CRSVP
• DIPsec

• B
  93% (42)
• C
  4% (2)
• D
  2% (1)

Explanation

BFD (Bidirectional Forwarding Detection) is used in Cisco SD-WAN to continuously measure link quality metrics such as latency, jitter, and packet loss across WAN tunnels, enabling the system to make intelligent path selection decisions. These probes run inside IPsec tunnels between vEdge/cEdge routers, providing real-time visibility into the health of each transport link.

Why the distractors are wrong:

• A. OMP (Overlay Management Protocol) is the SD-WAN control plane protocol used to exchange routing, policy, and reachability information between vSmart controllers and WAN Edge routers - it does not measure link quality.
• C. RSVP (Resource Reservation Protocol) is a traditional MPLS traffic engineering protocol used to reserve bandwidth along a path and has no role in Cisco SD-WAN.
• D. IPsec provides encryption and secure tunneling for SD-WAN data plane traffic, but it is not a measurement protocol - BFD actually runs within IPsec tunnels to do its testing.

Memory Tip: Think of BFD as a "link health doctor" - it constantly checks the pulse (latency, jitter, loss) of your WAN connections. The acronym can remind you: BFD = Bandwidth/link Fitness Detection.

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