What is the purpose of the fabric control plane in a Cisco SD-Access architecture?

In a Cisco SD-Access architecture, the fabric control plane, powered by LISP (Locator/ID Separation Protocol), is responsible for maintaining the Host Tracking Database (HTDB). This database stores and resolves endpoint-to-location mappings (EID-to-RLOC mappings), allowing the fabric to efficiently locate and route traffic to endpoints regardless of their physical location within the fabric, thus enabling mobility and simplified routing.

While BGP route reflectors might be used in the underlay for scale, creating a transit node with BGP route reflector functionality is an underlay routing concern, not the primary purpose of the fabric control plane (which is LISP-based).

Extending multiple subnets to one RLOC (Routing Locator) is a characteristic of LISP's operation, where multiple EIDs (Endpoint Identifiers) can map to a single RLOC, but it's a detail of how the mapping works rather than the overarching purpose of the control plane.

Group-Based Access Control (GBAC) policies are created and managed by Cisco DNA Center, and enforced by the fabric edge nodes and border nodes using Security Group Tags (SGTs), not directly by the LISP-based fabric control plane which focuses on location mapping.