350-401 Network Assurance Practice Question
A network engineer is deploying Cisco SD-Access and needs to ensure that fabric edge nodes can register with the fabric control plane node. Which protocol is used for this registration and for endpoint location mapping?
⚠ Common exam trap
Candidates often confuse the data plane protocol (VXLAN) with the control plane protocol (LISP), assuming that the encapsulation protocol also handles registration.
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
✓
LISP
In Cisco SD-Access, LISP is the control plane protocol that enables fabric edge nodes to register endpoints with the control plane node. The control plane node maintains a mapping database of endpoint identifiers to routing locators. VXLAN, BGP, and IS-IS serve other roles in the fabric, such as data plane encapsulation and underlay routing.
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 SD-Access for route distribution between fabric nodes, particularly in the underlay and for external connectivity. It is not used for endpoint registration or location mapping. The control plane node uses a different protocol to track endpoints. BGP is for routing, not endpoint identity.
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VXLAN
Why it's wrong here
VXLAN is used for data plane encapsulation in SD-Access, carrying traffic between fabric nodes. It does not handle endpoint registration or location mapping. While VXLAN provides the overlay transport, the control plane registration is handled by a different protocol. VXLAN is not used for registration.
- ✓
LISP
Why this is correct
LISP (Locator/ID Separation Protocol) is used in Cisco SD-Access for endpoint location mapping. Fabric edge nodes register endpoint EIDs with the control plane node, which maintains a mapping of EIDs to RLOCs. This allows the fabric to route traffic based on endpoint identity. LISP is the correct protocol for this function.
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IS-IS
Why it's wrong here
IS-IS is used in the SD-Access underlay for routing between fabric nodes. It provides the loopback reachability needed for VXLAN tunnels. However, it is not used for endpoint registration with the control plane node. IS-IS is a routing protocol, not a mapping protocol.
Go deeper
Related to this question
Learn chapter
Network Access Control and AAA
Key term
VXLAN
VXLAN is a network overlay technology that encapsulates Layer 2 Ethernet frames in UDP packets to extend VLANs across Layer 3 networks.
Key term
Fabric Fundamentals
Fabric Fundamentals is the set of core concepts behind a network fabric, where switches and routers form a single logical system that simplifies traffic forwarding and automation.
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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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