The Optical Internetworking Forum (OIF) announced that, following a 2014 prototype demonstration event, it has approved an SDN Framework white paper that is intended to pave the way for the implementation of SDN (software-defined networking) in Carrier Networks.
The OIF white paper, entitled Framework for Transport SDN: Components and APIs, outlines the SDN framework for multi-domain carrier networks and identifies critical open APIs for Transport SDN based on synthesis of the SDN layered architecture and the ITU-T ASON functional element model for optical network control.
SDN identifies interfaces separating the infrastructure and control layers, and the control layer from the application layer. The interface between infrastructure and control layers is termed the SouthBound Interface (SBI); the interface between control and application layers is termed the NorthBound Interface (NBI), and provides APIs to the application.
The OIF stated that a key finding of the prototype demonstration was that the separation enabled by the NBI and SBI allows SDN to be applied over both greenfield (i.e., OpenFlow) and brownfield environments, allowing the integration of domains controlled by management systems and domains using existing distributed control planes, as well as centralised SDN. A range of SBI protocols could coexist in a carrier's Transport SDN network, including the OpenFlow protocol, with extensions for optical networks.
The OIF also noted that NBI is a key area as, by providing access to ASON functional elements, it opens up access to the network control plane and provides greater programmability of services, thereby enhancing the speed of service deployment and overall manageability of the network. Functional elements accessible via NBI in the framework include call control, connection control, and topology and path computation.
The document assesses where existing protocols may be used to support NBI access, and also outlines the benefits from defining new REST-based interfaces, including those prototyped for the demonstration, based on a common information model.
A copy of the OIF framework document, Framework for Transport SDN: Components and APIs, is available here (registration required).
Regarding the demonstration, Lyndon Ong of Ciena and co-chair of the OIF market awareness and education committee, commented, "In 2014, the prototype demonstration brought together multiple vendors and carriers to test cloud-bursting services, utilising SDN principles and interfaces… the demonstration results factored into the development of a framework that allows SDN to be deployed over a carrier's network with multiple, diverse domains".