A fire district is building Cisco SD-Access and must ensure every fabric edge can reach every other fabric node’s underlay IP before any overlay VN comes up. What underlay design requirement does that statement describe?
Select an answer to reveal the explanation.
Short Explanation
The underlay is the paved roads; the overlay is the courier service riding on top. In SD-Access, every fabric node needs rock-solid IP reachability—often via IS-IS—before VXLAN/LISP magic matters. No roads, no overlay deliveries.
Full Explanation
Cisco SD-Access separates a routed underlay from the LISP/VXLAN overlay. Fabric nodes (edges, borders, control-plane nodes) require underlay IP connectivity so VTEP encapsulation and control-plane messaging can traverse the campus. Interior Gateway Protocols such as IS-IS are commonly used for that underlay; the overlay does not remove the need for independent underlay reachability.