S-Trace: Building Causal Paths on Software Defined Networks

Determining hardware and software elements used to process an application request and group them in a set, called causal path, that exposes relevant parameters, such as processing time and delays, and that may explain the behavior of the application is a challenging task. Several tools for building causal paths have been proposed for the current Internet architecture, but none so far explores features offered by Software Defined Network (SDN). This paper proposes S-Trace, a tool for building causal paths that does not modify applications and that uses specific features of SDN to build precise causal paths. To build a causal path, S-Trace intercepts library function calls to correlate communication events between processes and uses record and replay techniques in SDN to correlate network events. S-Trace was evaluated using a benchmark (TPC-W) and an application that emulates the behavior of multi-tier applications that was instrumented to validate the causal paths constructed by S-Trace. The experimental results show that S-Trace builds correct causal paths at the cost of a small overhead associated with some library function calls.