Izzy: A Distributed Routing Protocol for In-band SDN Control Channel Connectivity

Software-defined networking proposes to physically separate control and data plane. This raises the question on how these two planes communicate, especially if the control channel is in-band, i.e., it shares physical network paths with normal network traffic. In-band control requires calculating multi-hop paths between controller and switches. Connectivity of the control channel is critical regarding network operation. Routing should provide robust connectivity under failures.We propose to achieve robust connectivity by distributing responsibility of maintaining connectivity of the control channel to the switches. We further present the design of a new distributed routing protocol Izzy for in-band SDN control channels. Izzy is based on a combination of a spanning tree with temporary addresses and includes state-of-the-art robustness mechanisms. In this paper, we describe Izzy, while focusing on update consistency on top of temporary addresses.