The last two decades of network science have discovered stunning similarities in the topological characteristics of real life networks (many biological, social, transportation and organizational networks) on a strong empirical basis. However our knowledge about the operational paths used in these networks is very limited, which prohibits the proper understanding of the principles of their functioning. Today, the most widely adopted hypothesis about the structure of the operational paths is the shortest path assumption. Here we present a striking result that the paths in various networks are significantly stretched compared to their shortest counterparts. Stretch distributions are also found to be extremely similar. This phenomenon is empirically confirmed on four networks from diverse areas of life. We also identify the high-level path selection rules nature seems to use when picking its paths.

Humans are involved in various real-life networked systems. The most obvious examples are social and collaboration networks but the language and the related mental lexicon they use, or the physical map of their territory can also be interpreted as networks. How do they find paths between endpoints in these networks? How do they obtain information about a foreign networked world they find themselves in, how they build mental model for it and how well they succeed in using it? Large, open datasets allowing the exploration of such questions are hard to find. Here we report a dataset collected by a smartphone application, in which players navigate between fixed length source and destination English words step-by-step by changing only one letter at a time. The paths reflect how the players master their navigation skills in such a foreign networked world. The dataset can be used in the study of human mental models for the world around us, or in a broader scope to investigate the navigation strategies in complex networked systems.

Abstract-With the advent of online social media, latency became a primary factor and large Content Delivery Network (CDN) providers optimize their networks for. While many ingredients (e.g. propagation delay, transmission delay, processing delay) of the end-to-end latency can be adequately characterized, capturing queuing delay seems to be a difficult task due to the complex and often unpredictable nature of Internet paths and the imperfect tools used for measurements. Dealing with the queuing delay is so challenging that most papers concerning end-to-end latency completely ignore it for "simplicity". In this paper we take this view to the extreme and try to interpret the cause of various delays between the same endpoints as measurement artifacts, such as continuous changes in end-to-end paths and the imperfection of measurement tools. We arrive to the conclusion that there is a significant amount of points in endto-end delay measurements, which cannot be explained by these artifacts even if we do our best for doing so. The only plausible explanation for these points is the presence of significant queuing delay comparable with the delay caused by all the other factors (propagation, transmission and processing).

Abstract-In this demo, we show a novel method to multilayer service orchestration in a multi-domain network. This method is a basic implementation of the three layered concept with multi-layer orchestration designed by the UNIFY project. A global orchestrator is capable of instantiating service elements, i.e., virtual network functions (VNFs), in separate domains. Dedicated local orchestrators in different infrastructure domains are responsible for setting up new VNF instances and configuring the underlying network. Our implementation is based on the ESCAPE prototyping framework and an OpenStack (OS) data center with the OpenDaylight (ODL) controller.

Mininet is a great prototyping tool which combines existing SDN-related software components (e.g., Open vSwitch, OpenFlow controllers, network namespaces, cgroups) into a framework, which can automatically set up and configure customized OpenFlow testbeds scaling up to hundreds of nodes. Standing on the shoulders of Mininet, we implement a similar prototyping system called ESCAPE, which can be used to develop and test various components of the service chaining architecture. Our framework incorporates Click for implementing Virtual Network Functions (VNF), NETCONF for managing Click-based VNFs and POX for taking care of traffic steering. We also add our extensible Orchestrator module, which can accommodate mapping algorithms from abstract service descriptions to deployed and running service chains.