CCNP Network Assurance Practice Question
A network engineer is troubleshooting a Cisco SD-WAN deployment where a branch site is experiencing intermittent connectivity to the data center. The engineer suspects that the issue is related to the Bidirectional Forwarding Detection (BFD) configuration on the WAN Edge routers. Which Cisco SD-WAN component is responsible for establishing BFD sessions between WAN Edge routers?
⚠ Common exam trap
The trap here is assuming that the control plane component vSmart establishes BFD sessions because it manages routing; actually, BFD is a data plane function handled by WAN Edge routers.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
WAN Edge routers
In Cisco SD-WAN, BFD sessions are established between WAN Edge routers to monitor the health of the data plane tunnels. These sessions are used to detect failures and measure performance metrics. The WAN Edge routers are responsible for sending and receiving BFD packets. The other components (vManage, vBond, vSmart) are part of the management, orchestration, and control planes and do not establish BFD sessions. Thus, the WAN Edge routers are the correct answer.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
WAN Edge routers
Why this is correct
WAN Edge routers are responsible for establishing BFD sessions with each other. BFD is used to detect link failures and measure quality metrics such as latency, jitter, and packet loss. These sessions are established over the data plane, typically over IPsec tunnels or direct links. The WAN Edge routers send BFD packets periodically and use the results to make routing decisions. Therefore, they are the component that establishes and maintains BFD sessions.
- ✗
vSmart
Why it's wrong here
vSmart is the control plane component that distributes routing and policy information to WAN Edge routers. It establishes control connections with WAN Edge routers using OMP, but it does not establish BFD sessions. BFD is used for data plane liveness detection between WAN Edge routers. vSmart can influence BFD via policy, but it does not itself establish BFD sessions.
- ✗
vBond
Why it's wrong here
vBond is the orchestration plane component that handles initial authentication and NAT traversal. It helps WAN Edge routers discover each other and establish control connections, but it does not participate in BFD sessions. BFD sessions are data plane and are established directly between WAN Edge routers. vBond is not involved in the ongoing BFD operation.
- ✗
vManage
Why it's wrong here
vManage is the management plane component that provides a GUI for configuration, monitoring, and troubleshooting. It does not establish BFD sessions. It can display BFD session status and configure BFD parameters via templates, but the actual BFD packets are sent and received by the WAN Edge routers. Therefore, vManage is not responsible for establishing BFD sessions.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Cisco exam blueprint
This 350-401 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 350-401 exam.