The answer is the vEdge or cEdge router, as these edge devices are solely responsible for establishing and managing IPsec tunnels for the data plane in Cisco SD-WAN. This is correct because the SD-WAN architecture distributes the data plane entirely to the vEdge/cEdge routers, which use DTLS or TLS for control connections and then build their own IPsec tunnels directly with other branch routers to encrypt and authenticate traffic. This distributed model is what enables application-aware routing, as each router monitors real-time performance metrics like loss, latency, and jitter across its own encrypted tunnels and steers traffic accordingly. On the ENCOR 350-401 exam, this concept tests your understanding of the separation between the control plane (vSmart) and the data plane (vEdge/cEdge), with a common trap being to mistakenly assign tunnel management to the vSmart controller. Remember the memory tip: “vEdge does the edge work” — the edge routers handle the encrypted data tunnels, while the controller only orchestrates policies.
350-401 Enterprise Network Design Practice Question
This 350-401 practice question tests your understanding of enterprise network design. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
An enterprise is deploying Cisco SD-WAN and must ensure that data plane traffic between branch sites is encrypted and authenticated. The design must also allow the use of application-aware routing to steer traffic based on real-time performance metrics. Which component is responsible for establishing and managing the IPsec tunnels between branch routers?
Why wrong: vSmart controllers manage the control plane (OMP routes, policies) but do not terminate IPsec tunnels; they communicate with vEdge routers via DTLS/TLS.
B
vEdge/cEdge routers
vEdge/cEdge routers are the data plane devices that establish and terminate IPsec tunnels between branches, encrypting traffic and applying application-aware routing.
C
vManage
Why wrong: vManage is the management plane and does not participate in data plane tunnel establishment.
D
vBond
Why wrong: vBond is the orchestrator for initial authentication and NAT traversal, not for data plane tunnels.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
vEdge/cEdge routers
The vEdge/cEdge routers are the correct answer because they are the SD-WAN edge devices that terminate IPsec tunnels for data plane traffic. In Cisco SD-WAN, the data plane is fully distributed: each vEdge or cEdge router establishes and manages its own IPsec tunnels (using DTLS/TLS for control and IPsec for data) directly with other branch routers. This allows the routers to apply application-aware routing by monitoring real-time performance metrics (e.g., loss, latency, jitter) and steering traffic across the encrypted tunnels accordingly.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
vSmart controllers
Why it's wrong here
vSmart controllers manage the control plane (OMP routes, policies) but do not terminate IPsec tunnels; they communicate with vEdge routers via DTLS/TLS.
✓
vEdge/cEdge routers
Why this is correct
vEdge/cEdge routers are the data plane devices that establish and terminate IPsec tunnels between branches, encrypting traffic and applying application-aware routing.
Related concept
Read the scenario before looking for a memorised answer.
✗
vManage
Why it's wrong here
vManage is the management plane and does not participate in data plane tunnel establishment.
✗
vBond
Why it's wrong here
vBond is the orchestrator for initial authentication and NAT traversal, not for data plane tunnels.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that vSmart controllers handle all tunnel management, but in SD-WAN, vSmart only distributes policies and OMP routes, while the actual IPsec tunnel establishment and data plane forwarding is a function of the vEdge/cEdge routers.
Detailed technical explanation
How to think about this question
Under the hood, each vEdge/cEdge router maintains a separate IPsec tunnel (using IKEv2 or pre-shared keys) to every other vEdge/cEdge router it needs to communicate with, forming a full mesh or hub-and-spoke topology. The routers use Bidirectional Forwarding Detection (BFD) over these tunnels to measure real-time performance metrics (loss, latency, jitter) at sub-second intervals, which feeds into the application-aware routing engine. In a real-world scenario, if a branch router detects increased latency on one tunnel, it can dynamically steer VoIP traffic to an alternate tunnel without controller intervention.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 350-401 question in full detail.
Enterprise Network Design — This question tests Enterprise Network Design — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: vEdge/cEdge routers — The vEdge/cEdge routers are the correct answer because they are the SD-WAN edge devices that terminate IPsec tunnels for data plane traffic. In Cisco SD-WAN, the data plane is fully distributed: each vEdge or cEdge router establishes and manages its own IPsec tunnels (using DTLS/TLS for control and IPsec for data) directly with other branch routers. This allows the routers to apply application-aware routing by monitoring real-time performance metrics (e.g., loss, latency, jitter) and steering traffic across the encrypted tunnels accordingly.
What should I do if I get this 350-401 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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