Convergence of Probability Measures. By P. Billingsley. Chichester, Sussex, Wiley, 1968. xii, 253 p. 9 1/4“. 117s.

Convergence of Probability Measures

Social Network Analysis

The Internet has led to the creation of a digital society, where (almost) everything is connected and is accessible from anywhere. However, despite their widespread adoption, traditional IP networks are complex and very hard to manage. It is both difficult to configure the network according to predefined policies, and to reconfigure it to respond to faults, load, and changes. To make matters even more difficult, current networks are also vertically integrated: the control and data planes are bundled together. Software-defined networking (SDN) is an emerging paradigm that promises to change this state of affairs, by breaking vertical integration, separating the network's control logic from the underlying routers and switches, promoting (logical) centralization of network control, and introducing the ability to program the network. The separation of concerns, introduced between the definition of network policies, their implementation in switching hardware, and the forwarding of traffic, is key to the desired flexibility: by breaking the network control problem into tractable pieces, SDN makes it easier to create and introduce new abstractions in networking, simplifying network management and facilitating network evolution. In this paper, we present a comprehensive survey on SDN. We start by introducing the motivation for SDN, explain its main concepts and how it differs from traditional networking, its roots, and the standardization activities regarding this novel paradigm. Next, we present the key building blocks of an SDN infrastructure using a bottom-up, layered approach. We provide an in-depth analysis of the hardware infrastructure, southbound and northbound application programming interfaces (APIs), network virtualization layers, network operating systems (SDN controllers), network programming languages, and network applications. We also look at cross-layer problems such as debugging and troubleshooting. In an effort to anticipate the future evolution of this new paradigm, we discuss the main ongoing research efforts and challenges of SDN. In particular, we address the design of switches and control platforms—with a focus on aspects such as resiliency, scalability, performance, security, and dependability—as well as new opportunities for carrier transport networks and cloud providers. Last but not least, we analyze the position of SDN as a key enabler of a software-defined environment.

https://publications.uni.lu/bitstream/10993/20596/1/survey_on_SDN.pdf

Software-Defined Networking: A Comprehensive Survey

Infectious Diseases Society of America.

The structure and dynamics of multilayer networks

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.

/pdf/qoe-lab-towards-evaluating-quality-of-experience-for-future-28lq0pqyqk.pdf

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

More than half of Internet traffic today is contributed by peer-to-peer (P2P) systems. Yet P2P systems build their overlay topology largely agnostic of the Internet underlay, which often leads to traffic management challenges for Internet Service Providers (ISP) and potentially inefficient neighbourhood selection for P2P nodes. To overcome this, we propose to use an oracle hosted by the ISPs, so that ISPs and P2P users can cooperate for improved performance. The oracle can be queried by P2P nodes while choos- ing neighbours for content search, and it will rank the possible neighbours of the querying node according to a locality indication, like location within the same AS, or the AS-hop distance. The ISP gains by keeping traffic within its Autonomous System (AS), and the P2P node can experience improved performance like lesser delay and better bandwidth.
 
In this paper, we evaluate the benefits of our scheme by performing experiments in a real Testlab as well as a simulation framework. We show how we configure representative AS topologies for P2P networks, and present experimental results with content search phase of a P2P network using different file sharing and search query distributions.

Locality-aware P2P query search with ISP collaboration

After almost two decades of IPv6 development and consequent efforts to promote its adoption, the current global share of IPv6 traffic still remains low. Urged by the need to understand the reasons that slow down this transition, the research community has devoted much effort to characterize IPv6 adoption, i.e., if ISPs and content providers enable IPv6 connectivity. However, little is known about how much the available IPv6 connectivity is actually used and precisely which factors determine whether data is exchanged over IPv4 or IPv6. To tackle this question, we leverage a relevant vantage point: a dual-stack residential broadband network. We study interactions between applications, devices, equipment and services, and illustrate how these interactions ultimately determine the IPv6 traffic share. Lastly, we elaborate on the potential scenarios that dual-stack ISPs and content providers may confront during the Internet’s transition to IPv6.

Understanding the Share of IPv6 Traffic in a Dual-Stack ISP

Virtual switches are a crucial component of cloud operating systems that interconnect virtual machines in a flexible manner. They implement complex network protocol parsing in the unified packet parser - parsing all supported packet header fields in a single pass - and are commonly co-located with the virtualization layer. We find that this significantly reduces the barrier for low-budget attackers to launch high impact attacks in the cloud. This leads us to introduce the virtual switch attacker model for packet-parsing, in short the vAMP attack. Using OpenStack, a cloud operating system, and Open vSwitch, a virtual switch, we demonstrate how current virtual switch designs cannot withstand vAMP. Thereby giving a weak attacker full control of the cloud in a matter of minutes

The vAMP Attack: Taking Control of Cloud Systems via the Unified Packet Parser

Web performance is widely studied in terms of load times, numbers of objects, object sizes, and total page sizes. However, for all these metrics, there are various definitions, data sources, and measurement tools. These often lead to different results and almost all studies do not provide sufficient details about the definition of metrics and the data sources they use. This hinders reproducibility as well as comparability of the results. This paper revisits the various definitions and quantifies their impact on performance results. To do so we assess Web metrics across a large variety of Web pages.

/pdf/web-performance-pitfalls-2nnirw80o0.pdf

Anja Feldmann

Papers

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

Locality-aware P2P query search with ISP collaboration

Understanding the Share of IPv6 Traffic in a Dual-Stack ISP

The vAMP Attack: Taking Control of Cloud Systems via the Unified Packet Parser

Web Performance Pitfalls