Among the different options to instantiate overlays, the Locator/ID Separation Protocol (LISP) [7] has gained significant traction among industry and academia [5], [6], [8]–[11], [14], [15]. Interestingly, LISP offers a standard, inter-domain, and dynamic overlay that enables low capital expenditure (CAPEX) innovation at the network layer [8]. LISP follows a map-and-encap approach where overlay identifiers are mapped to underlay locators. Overlay traffic is encapsulated into locator-based packets and routed through the underlay. LISP leverages a public database to store overlay-to-underlay mappings and on a pull mechanism to retrieve those mappings on demand from the data plane. Therefore, LISP effectively decouples the control and data planes, since control plane policies are pushed to the database rather than to the data plane. Forwarding elements reflect control policies on the data plane by pulling them from the database. In that sense, LISP can be used as an SDN southbound protocol to enable programmable overlay networks [5].

Peer Reviewed