正解:C
The correct answer is C. using BFD.
In Cisco Catalyst SD-WAN, the health of data plane tunnels is monitored using Bidirectional Forwarding Detection (BFD). Cisco documentation states that BFD runs over all data plane tunnels between Cisco IOS XE Catalyst SD-WAN devices and is used to monitor the liveness and path characteristics of those tunnels, including loss, jitter, and latency.
BFD is the protocol specifically used in Cisco SD-WAN to detect tunnel failures quickly and measure tunnel quality. These measurements are also used by SD-WAN features such as application-aware routing to make path-selection decisions.
* A. with IP SLA IP SLA is a Cisco feature for measuring network performance in many environments, but Cisco SD-WAN data plane tunnel health is monitored with BFD, not IP SLA.
* B. with OMP OMP (Overlay Management Protocol) is the control-plane routing protocol in Cisco SD- WAN. It distributes routes, TLOCs, and service information, but it does not monitor data plane tunnel health.
* D. ARP probing ARP is used for Layer 2/neighbor resolution on local segments and is not the tunnel- health monitoring mechanism for SD-WAN data plane tunnels.
ENCOR exam point:
In Cisco Catalyst SD-WAN:
* OMP = control-plane route exchange
* BFD = data-plane tunnel liveliness and performance monitoring