CCNP Architecture Practice Question
A network architect is designing a Cisco SD-WAN fabric for a retail chain with 200 branch sites. The design must provide a single control-plane protocol that distributes routing and policy information between the SD-WAN controllers and the WAN Edge devices, while keeping data-plane traffic direct between branches. Which technology should the architect select for the control plane?
⚠ Common exam trap
The trap here is assuming that any routing protocol carrying prefixes between WAN Edge devices can serve as the SD-WAN fabric control plane, when only OMP provides TLOC and centralized policy distribution.
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
✓
Cisco Overlay Management Protocol (OMP)
Cisco SD-WAN uses OMP as the single control-plane protocol between the vSmart controller and WAN Edge devices. OMP carries TLOC, route, and policy information, allowing the controller to make forwarding decisions while data traffic flows directly between branches. BGP and IS-IS are underlay or service-side protocols, and LISP belongs to SD-Access, so they do not meet the stated design requirement.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Intermediate System-to-Intermediate System (IS-IS)
Why it's wrong here
IS-IS is a link-state interior gateway protocol used for underlay routing, not for SD-WAN overlay control. It does not distribute TLOCs, OMP routes, or centralized policy between controllers and WAN Edge devices. Deploying IS-IS would provide IP reachability but would not fulfill the SD-WAN control-plane requirement described.
- ✗
Locator/ID Separation Protocol (LISP)
Why it's wrong here
LISP is the control-plane protocol used in Cisco SD-Access for the fabric overlay, not in Cisco SD-WAN. Although both are Cisco architectures, LISP handles endpoint identifier-to-routing locator mappings in a campus fabric. Selecting LISP for an SD-WAN fabric would be a technology mismatch, so this option does not satisfy the scenario.
- ✓
Cisco Overlay Management Protocol (OMP)
Why this is correct
OMP is the SD-WAN control-plane protocol that runs between WAN Edge devices and the vSmart controller over DTLS/TLS. It advertises TLOCs, service-side routes, and centralized policy, enabling the controller to orchestrate fabric reachability without hairpinning data traffic. This matches the requirement of a single control plane with direct branch-to-branch data forwarding, so it is the correct choice.
- ✗
Border Gateway Protocol (BGP) with route reflectors
Why it's wrong here
BGP can carry routing information between WAN Edge devices, but in Cisco SD-WAN it is used on the service side or for controller peering, not as the primary fabric control plane. It cannot distribute TLOC attributes or centralized policy in the SD-WAN overlay. Relying on BGP alone would not meet the single-protocol control-plane requirement, making this option incorrect.
About these practice questions
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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.