SPRM: Source Path Routing Model and Link Failure Handling in Software-Defined Networks

Software Defined Networking (SDN) has emerged as a promising paradigm with the key idea of separating control and data planes. However, this separation causes various scalability issues (e.g., increased response time, overhead on the controller and core SDN switches) in Wide Area Networks (WANs). While addressing such scalability issues, it is important to maintain the performance gains of the Reactive SDN and also to handle link failures. To jointly address scalability, performance, and link failure issues, we propose a new
Source-Path Routing Model (SPRM)
by combining the best of proactive and reactive approaches along with a simple packet programming mechanism. Specifically, SPRM pre-calculates and pre-installs multiple paths (proactive part) but then selects/assigns one of these paths for an incoming flow based on the available dynamic network state information (NSI) (reactive part). We also utilize SPRM to effectively cope with the link failures by using multiple paths as backup to each other. Our simulation results show that SPRM performs much better than the pure Reactive SDN in terms of path establishment delay and flow table size while (a) maintaining its performance gains in terms of link utilization and load balancing, and (b) quickly recovering from a link failure without causing extra memory overhead on the data plane.