Due to the great potentials brought by the unique attractive features, SDN is gradually adopted by Data Center Networks (DCNs) and carrier networks. The operator of a large-scale enterprise / carrier network should divide the whole networks into multiple connected SDN domains, where each of such domains corresponds to a relatively small portion of the whole network. Such a divide-and-conquer methodology not only allows gradual deployment and continuous evolution, but also enables flexible provisioning of the network. With the deployment of multiple SDN domains comes the issue of exchanging information between these domains.
SDNi is a protocol for interfacing SDN domains. It is responsible for coordinating behaviorseamless_mpls.jpgs between SDN controllers and exchange control and application information across multiple SDN domains. SDNi is an "east-west" protocol between SDN controllers, as an analogy to OpenFlow being a "north-south" protocol between controller and Network devices. (IETF Internet-Draft, "Software Defined Networking Debuted at IETF", the IETF Journal, October, 2012)
SDNi protocol should be able to:
The types of messages exchanged via SDNi can be:
SDNi is used to exchange information between SDN domains that are under the control of a single network operator or collaborating operators. One way to implement SDNi is to use extension of BGP and SIP over SCTP protocols to exchange information.