Fabric, SD-Access, LISP & SD-WAN

Fabric thinking: a big L2-ish reach (VXLAN overlay) over a simple routed underlay, with identity and policy decoupled from IP subnets. SD-Access roles Control-plane node: runs LISP mapping — answers “where is this host?” Edge node: encapsulates into the fabric, enforces policy at entry. Border node: fabric ↔ outside world; border + edge (FGP) for […]

SDN — Centralised Control Plane

SDN is an architecture, not a protocol: separate control plane from data plane, put the brain in a controller, program devices over APIs. Southbound: OpenFlow/NETCONF/RESTCONF; northbound: REST for applications. (“SDN = OpenFlow” is the classic false statement — OpenFlow is one implementation.) Devices become flow-table forwarders; the controller computes paths and installs entries. Design prerequisites: […]