How Does vManage Interact with Cisco SD-WAN Devices in the Fabric?

350-401 By islever Editorial Last updated

Short answer

D southbound API

Question

What is used by vManage to interact with Cisco SD-WAN devices in the fabric?
  1. IPsec
  2. northbound API
  3. RESTCONF
  4. southbound API Correct Answer

Key Takeaways

This question tests your understanding of API directionality in SDN/SD-WAN: southbound = controller-to-device, northbound = controller-to-application.

vManage uses southbound APIs to communicate with and manage Cisco SD-WAN devices (vEdges, cEdges, vSmart) within the fabric, while northbound APIs are reserved for integration with external applications and orchestration systems.

Common mistake: Many candidates choose 'northbound API' because vManage itself is often described as the 'northbound' management plane relative to vSmart, confusing the perspective of the API direction.

Expert Analysis

Understanding Southbound vs. Northbound APIs in Cisco SD-WAN

In the Cisco SD-WAN architecture, vManage is the centralized management and orchestration platform. To communicate with the actual network devices in the fabric—such as vEdge routers, cEdge routers, and vSmart controllers—vManage relies on southbound APIs.

Why the Answer is D (Southbound API)

A southbound API is the interface through which a controller or management plane communicates downward to the underlying network devices it manages. In Cisco SD-WAN, vManage uses southbound APIs (often based on NETCONF, RESTCONF, or proprietary protocols over DTLS/TLS tunnels) to push configurations, retrieve telemetry, and enforce policies on the fabric devices. As community member hugoplur correctly notes, southbound APIs are used to "enforce policies, configure settings, and manage the overall network."

Why the Other Options Are Incorrect

  • A (IPsec): While IPsec (specifically DTLS or IPsec tunnels) is used as the transport for control and data plane communication between SD-WAN components, it is not the API mechanism itself. IPsec secures the channel; it is not the API.
  • B (Northbound API): This is the most common trap. A northbound API allows vManage to communicate upward to external applications, orchestration platforms, or third-party systems (e.g., ServiceNow, custom dashboards). It is not used to talk to the fabric devices themselves. Community members MrG and cwauch clearly distinguish: "Southbound APIs interact with fabric devices. Northbound APIs interact with applications."
  • C (RESTCONF): RESTCONF is a specific protocol that can be used as a southbound API mechanism, but the question asks for the general concept. Moreover, vManage's primary southbound communication with vEdges/cEdges historically uses proprietary protocols and NETCONF, not exclusively RESTCONF. RESTCONF is more commonly associated with northbound or device-level management, making it a less accurate answer than the broader "southbound API."

Key Takeaway

Always think of the SDN controller as the reference point:

  • Southbound = Controller → Devices (vManage → vEdge/cEdge/vSmart)
  • Northbound = Controller → Applications/External Systems (vManage → ServiceNow, Python scripts, etc.)

Community consensus strongly supports D (77%), with only a minority confused by the northbound terminology.

Exam Strategy

When you see 'API direction' questions in SDN/SD-WAN exams, always anchor your thinking to the controller: southbound means 'down to devices,' northbound means 'up to apps.' Eliminate transport-layer answers like IPsec immediately.

Community Votes

D
77%
B
23%

77% of anonymous learners picked answer D. Votes are pick records left by other test-takers — they are not the verified answer.

Discussion 12 contributions

Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.

From public community threads 12

  1. [Removed] 👍 14
    vManage interacts with Cisco SD-WAN devices in the fabric using southbound APIs. These APIs facilitate communication and management of the network devices. D. southbound API
  2. lohitnadimpalli 👍 7
    Answer is D vManage uses a southbound API to interact with Cisco SD-WAN devices in the fabric. In the context of software-defined networking (SDN) and network management, a southbound API is an interface that enables a controller or management system (like vManage) to communicate with and control the underlying network devices (such as vEdge routers, cEdge routers, and vSmart controllers in the Cisco SD-WAN fabric).
  3. cwauch 👍 6 Answered D
    Southbound APIs interact with fabric devices. Northbound APIs interact with applicatons.
  4. hugoplur 👍 3 Answered D
    Southbound API: In the context of Cisco SD-WAN, vManage uses southbound APIs to interact with the SD-WAN devices in the network fabric. Southbound APIs are used by a controller to communicate with the network devices (such as routers and switches) to enforce policies, configure settings, and manage the overall network.
  5. MrG 👍 3 Answered D
    A Northbound API is used to communicate upward from a controller (in this case, vManage) to external applications or systems. A Southbound API is used to communicate downward from a controller to the devices it manages.
Show 7 more comments
  1. [Removed] 👍 2 Answered D
    D is correct don't make it complicated about it, controller to devices = South application to the controller: North
  2. babanaber 👍 1 Answered B
    https://www.networkacademy.io/ccie-enterprise/sdwan/cisco-sd-wan-rest-apis#:~:text=Cisco%20SD%2DWAN%20has%20been%20designed%20with%20automation%20and%20extensibility%20in%20mind.%20Cisco%20vManage%20provides%20northbound%20RESTful%20APIs
  3. Beehurls 👍 1 Answered B
    I'm going with Northbound APIs. The comments are talking about controllers managing devices, but vSmart is the controller. vManage is the human interface which is "north" of the controllers.
  4. abc112233 👍 1
    why not c, north is for upperlayer app, south is vsmart to edge
  5. chiacche 👍 3 Answered D
    devices -> SB
  6. Adalberto 👍 1 Answered B
    Answear is B
  7. Adalberto 👍 1 Answered B
    Answer is B

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