SD-Access Border Node Encapsulates/De-encapsulates VXLAN

300-420 By islever Editorial Last updated

Describe SD-Access Architecture (underlay, overlay, control and data plane, automation, wireless, and security)

Short answer

B The SD-Access border node encapsulates and de-encapsulates VXLAN traffic between the fabric and external networks.

Question

What is the purpose of a border node in a Cisco SD-Access fabric?
  1. expand a network
  2. perform traffic encapsulation and de-encapsulation Correct Answer
  3. connect devices to a network
  4. perform network virtualization

Key Takeaways

Border = fabric-to-external interworking via VXLAN encapsulation/de-encapsulation. Edge nodes connect endpoints; the border handles external reachability and network-virtualization interworking.

In a Cisco SD-Access fabric, the border node is the gateway between the fabric and external networks. It de-encapsulates VXLAN from the fabric to external destinations and encapsulates external traffic back into VXLAN when entering the fabric. It is not primarily where endpoints connect (edge nodes do that).

Common mistake: Picking D (perform network virtualization): the border does network-virtualization interworking, but its defining forwarding role is VXLAN encapsulation/de-encapsulation (B); D is a partial/distractor phrasing per Cisco docs.

Expert Analysis

Why the Answer Is Correct

B is correct. The border node's core function is VXLAN encapsulation and de-encapsulation at the fabric edge: it removes the VXLAN wrapper for traffic leaving the fabric and adds it for traffic entering the fabric from external networks.

Why the Other Options Are Wrong

A (expand a network) is vague and not the border's role. C (connect devices to a network) describes fabric edge nodes, not the border. D (perform network virtualization) is interworking the border does, but the specific forwarding action tested is encapsulation/de-encapsulation (B).

Community Comment Notes

The vote is B (100). Commenters confirm the border de-encapsulates VXLAN from fabric to external and encapsulates external-to-fabric; some note D is a distractor per the SDA design guide.

Official Reference

https://www.cisco.com/c/en/us/solutions/enterprise-networks/software-defined-access.html

This link opens the official vendor documentation in a new tab.

Community Votes

B
100%

100% of anonymous learners picked answer B. Votes are pick records left by other test-takers — they are not the verified answer.

Discussion 5 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 5

  1. PicoOstrava 👍 2 Answered B
    I believe the trap here is that the border node in a Cisco SD-Access fabric does not perform network virtualization itself; as per Cisco U materials: The fabric border node is responsible for network virtualization “interworking” and as mentioned bellow: The border node can "extend" network virtualization https://www.cisco.com/c/en/us/td/docs/solutions/CVD/Campus/cisco-sda-design-guide.html#Border_Node Meanwhile its clearly stated: VXLAN encapsulation/de-encapsulation—Packets and frames received from outside the fabric and destined for an endpoint inside of the fabric are encapsulated in fabric VXLAN by the border node
  2. Seb82 👍 1
    Based on this link, both B and D are candidates for a correct answer https://www.cisco.com/c/en/us/td/docs/solutions/CVD/Campus/cisco-sda-design-guide.html#Border_Node
  3. kuttatnl 👍 1 Answered B
    B is correct, From Fabrci to extenal world the border will deencapsulate vxlan packets and external to Fabric encapsulate the Vxlan packet.
  4. 5c725f5 👍 1 Answered B
    The options here are a little vague but B is closest to what a Border Node does in my view
  5. Swiz005 👍 1
    Can anyone confirm D to be the answer? - I would have thought A?

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