Achieving dependability in software-defined networking - a perspective

Abstract

In this paper we take a closer look at the operationof software defined networking (SDN) in intra-domain networks.The focus is on the dependability issues related to interworking ofSDN controllers, network OS (NOS), and forwarding in the dataplane. Both the separation of the control and data planes, and the(virtually) centralized control processes, are challenging from adependability perspective. In particular, consistency in operationand information is a challenge, both between the control and dataplanes, but also within a given plane. To ensure the necessarylevel of consistency there could be a conflict with the strict real-time requirements given by the per-flow operation of the SDNcontroller. A principle system model is introduced to discussthe consistency challenge, and to point out undesirable cyclicdependencies between functions that are necessary to configureand operate SDN. The separation of control processing andforwarding do also introduce structural vulnerabilities, whichare exemplified