350-401 Architecture Practice Question
A network administrator is deploying a Cisco SD-WAN solution. The administrator wants to ensure that control plane information is securely distributed between vSmart controllers and vEdge routers. Which protocol does Cisco SD-WAN use for this purpose?
⚠ Common exam trap
Many exam-takers confuse the transport security protocol (DTLS) with the actual control plane routing protocol (OMP), or assuming that BGP is used for overlay control when it is only used for external route exchange.
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
✓
OMP
Cisco SD-WAN uses Overlay Management Protocol (OMP) for control plane communication between vSmart controllers and vEdge routers. OMP distributes routing, policy, and service information, and it runs over secure TLS/DTLS sessions. While BGP, IPsec, and DTLS play roles in SD-WAN, OMP is the specific control plane protocol that enables the overlay network's dynamic routing and policy enforcement.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
BGP
Why it's wrong here
BGP is used in Cisco SD-WAN for route exchange with external networks, such as between vEdge routers and service providers, but it is not the control plane protocol between vSmart controllers and vEdge routers. OMP is used for that purpose. BGP does not provide the overlay control plane functions that OMP does.
- ✗
IPsec
Why it's wrong here
IPsec is used for data plane encryption between vEdge routers in Cisco SD-WAN. It secures the actual traffic traversing the overlay tunnels. However, it is not the control plane protocol for distributing routing and policy information between vSmart controllers and vEdge routers. OMP handles that role.
- ✗
DTLS
Why it's wrong here
DTLS (Datagram Transport Layer Security) is used to secure the control plane communication between vSmart controllers and vEdge routers, but it is a transport security protocol, not the routing protocol itself. OMP runs over DTLS or TLS. The question asks for the protocol used for control plane information distribution, which is OMP.
- ✓
OMP
Why this is correct
Overlay Management Protocol (OMP) is the control plane protocol used in Cisco SD-WAN. It runs between vSmart controllers and vEdge routers to distribute routing, policy, and service information securely. OMP uses TLS for encryption and authentication, ensuring secure communication. It is the correct protocol for this requirement.
Quick reference
VPN Protocol Comparison
| Protocol | Port | Encryption | Authentication | Use Case |
|---|---|---|---|---|
| IKEv2 / IPsec | UDP 500 / 4500 | AES-256 | Certificates / PSK | Site-to-site & remote access |
| SSL / TLS VPN | TCP 443 | TLS 1.3 | Certificates / MFA | Clientless remote access |
| L2TP / IPsec | UDP 1701 | AES (IPsec) | PSK / Certificates | Legacy remote access |
| WireGuard | UDP 51820 | ChaCha20 | Public keys | Modern high-performance VPN |
| PPTP | TCP 1723 | MPPE (weak) | MS-CHAPv2 | Legacy — avoid in production |
PPTP is considered insecure. IKEv2/IPsec and SSL VPN are the current recommended options.
Go deeper
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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
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