The correct answer is D. It provides isolation among the virtual networks and independence from the physical network.
Cisco SD-Access is based on two main layers:
* Underlay network # Physical infrastructure (routers, switches, IP connectivity)
* Overlay network # Virtualized logical network built on top of the underlay According to Cisco ENCOR architecture principles, the overlay network:
* Uses technologies like LISP (control plane) and VXLAN (data plane)
* Creates virtual networks (VNs) for segmentation
* Provides end-to-end logical separation (macro-segmentation)
* Is independent of the physical topology
* Enables scalable and flexible network design
Thus, the overlay abstracts the complexity of the underlay and ensures isolation between different user groups, departments, or tenants.
* Directly describes virtual network segmentation
* Matches Cisco's definition of overlay abstraction and independence
* Core principle of SD-Access fabric design
* A. Multicast and Layer 2 flooding relate more to underlay or legacy designs, not overlay behavior.
* B. Describes the underlay network (physical devices), not overlay.
* C. Refers to traditional network design, which SD-Access replaces.
* Underlay = Physical IP network (reachability)
* Overlay = Virtual segmentation & policy (VXLAN + LISP)
Overlay = Abstraction + Segmentation + Independence