Andreas Wundsam

Network virtualization architecture: proposal and initial prototype

The tussle between reliability and functionality of the Internet is firmly biased on the side of reliability. New enabling technologies fail to achieve traction across the majority of ISPs. We believe that the greatest challenge is not in finding solutions and improvements to the Internets many problems, but in how to actually deploy those solutions and re-balance the tussle between reliability and functionality. Network virtualization provides a promising approach to enable the coexistence of innovation and reliability. We describe a network virtualization architecture as a technology for enabling Internet innovation. This architecture is motivated from both business and technical perspectives and comprises four main players. In order to gain insight about its viability, we also evaluate some of its components based on experimental results from a prototype implementation.

Troubleshooting blackbox SDN control software with minimal causal sequences

Software bugs are inevitable in software-defined networking control software, and troubleshooting is a tedious, time-consuming task. In this paper we discuss how to improve control software troubleshooting by presenting a technique for automatically identifying a minimal sequence of inputs responsible for triggering a given bug, without making assumptions about the language or instrumentation of the software under test. We apply our technique to five open source SDN control platforms---Floodlight, NOX, POX, Pyretic, ONOS---and illustrate how the minimal causal sequences our system found aided the troubleshooting process.

NOSIX: a lightweight portability layer for the SDN OS

In spite of the standardization of the OpenFlow API, it is very difficult to write an SDN controller application that is portable (i.e., guarantees correct packet processing over a wide range of switches) and achieves good performance (i.e., fully leverages switch capabilities). This is because the switch landscape is fundamentally diverse in performance, feature set and supported APIs. We propose to address this challenge via a lightweight portability layer that acts as a rendezvous point between the requirements of controller application and the vendor knowledge of switch implementations. Above, applications specify rules in virtual flow tables annotated with semantic intents and expectations. Below, vendor specific drivers map them to optimized switch-specific rule sets. NOSIX represents a first step towards achieving both portability and good performance across a diverse set of switches.

QoE-Lab: Towards Evaluating Quality of Experience for Future Internet Conditions

Multimedia applications have recently been challenging existing mobile access networks and are raising the bar for next generation mobile networks (NGMN), both in terms of network traffic as well as in the expectations of end users. At the same time, the network and server landscape sees changes due to the advent of virtualization and split-architecture networks like OpenFlow. In this heterogeneous environment, quantitative measurement and prediction of the user’s Quality of Experience (QoE) require testbeds capable of studying these effects combined as well as in isolation, in a controlled and reproducible manner. In this paper, we present the design and architecture of QoE-Lab, a multi-purpose heterogeneous testbed that supports a variety of networking conditions to evaluate QoE in future Internet scenarios. QoE-Lab includes 1) NGMN networks, 2) access/backbone network emulation, and 3) virtualization. It provides services like traffic generation, topology emulation and high-precision cross-layer monitoring. The experiments are provisioned, orchestrated and analyzed by a tool called ExpAuto. We analyze the experimental results for relationships between network performance and user perception. We report initial results from our studies, qualitatively indicating that each of the discussed components has a significant impact on the QoE.

Network troubleshooting with Mirror VNets

Today diagnosing problems, deploying new services, testing protocol interactions, or validating network configurations are still largely unsolved problems for both enterprise and Internet Service Provider (ISP) networks. Due to the intrinsically distributed nature of network state, frequent timing dependencies, and sources of non-determinism involved, any change may introduce undesired effects-even the impact of a simple configuration change can be hard to predict. In this paper we show how to leverage network virtualization to improve our debugging ability: By replicating and cloning production networks and then applying the changes to the cloned network in a safe fashion. Mirror VNets thus enable troubleshooting as well as safe upgrades to both software and configuration.

Potential Benefit of Flow-based Routing in Multihomed Environments

SUMMARY The data rates provisioned by broadband Internet access connections continue to fall short of the requirements posed by emerging applications. However, the potential of statistical multiplexing of the last mile broadband connections remains unexploited even as the average utilisation of these connections remains low. Despite recent work in this area, two key questions remain unanswered: (a) what is the attainable benefit of broadband access sharing? and (b) how much of this benefit is realisable given real-world constraints? In this work we quantify the attainable benefit of a multihomed broadband access environment by proposing and evaluating several flow-based access sharing policies using a custom flow-based simulator. We then analyse how much of the performance benefit is lost due to real-world constraints by migrating from simulations to a test-lab environment employing a wireless network. Our results show that in today’s broadband Internet access scenarios, a significant reduction in download times (up to a factor of 3) is achievable. Copyright

Berlin: The Berlin Experimental Router Laboratory for Innovative Networking

Today’s disruptive approaches to rearchitecting the Internet, e.g., Clean Slate Networking initiatives require testbeds that present unprecedented flexibility to the experimenter. This poster presents Berlin, a flexible testbed platform designed towards the requirements of Future Internet research. Berlin combines a diverse landscape of network elements, both software-defined and legacy hardware, and unifies them under a common management interface, presenting them as pluggable services to the experimenter.