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HyFI: Hybrid Flow Initiation in Software Defined Networks

Software defined networking (SDN) provides techniques to facilitate the management of computer networks in a centralized and integrated architecture by separating the control plane from the data plane in packet forwarding devices and middleboxes. By creating this abstraction layer, SDN allows control of network middleboxes remotely from a controller point, which is either connected directly (out-of-band control using dedicated links) or indirectly (in-band control using the available data network links) to the middleboxes. Flow initiation methods used for unknown flows in out-of-band control mechanism are not optimized for use in in-band controllers. Therefore, handling flow initiation and controller discovery for hybrid SDN's and cases where the control and data traffic flow on the same network are still challenges yet to be addressed. The present study first includes a review of the current state-of-the-art in tackling flow initiation challenge and then addresses the problem in SDN's with in-band controllers by proposing a hybrid mechanism that aims to minimize the delay in the transmission of new flows during flow initiation. Our proposal uses a unified network map on the controller to form apriori network information and then configures the switches appropriately. By modeling flow initiation in OpenFlow, the present study also compares the implications of the proposal with the flow initiation methods currently used in out-of-band controllers today.