PATHspider: A tool for active measurement of path transparency

In today’s Internet we see an increasing deployment of middleboxes. While middleboxes provide in-network functionality that is necessary to keep networks manageable and economically viable, any packet mangling – whether essential for the needed functionality or accidental as an unwanted side effect – makes it more and more difficult to deploy new protocols or extensions of existing protocols. For the evolution of the protocol stack, it is important to know which network impairments exist and potentially need to be worked around. While classical network measurement tools are often focused on absolute performance values, we present a new measurement tool, called PATHspider that performs A/B testing between two different protocols or different protocol extension to perform controlled experiments of protocol-dependent connectivity problems as well as differential treatment. PATHspider is a framework for performing and analyzing these measurements, while the actual A/B test can be easily customized. This paper describes the basic design approach and architecture of PATHspider and gives guidance how to use and customize it.