How many links can be cut before a network is bisected? What is the maximal bandwidth that can be pushed between two nodes of a network? These questions are closely related to network resilience, path choice for multipath routing or bisection bandwidth estimations in data centers. The answer is quantified using metrics such as the number of edge-disjoint paths between two network nodes and the cumulative bandwidth that can flow over these paths. In practice though, such calculations are far from simple due to the restrictive effect of network policies on path selection. Policies are set by network administrators to conform to service level agreements, protect valuable resources or optimize network performance. In this work, we introduce a general methodology for estimating lower and upper bounds for the policy-compliant path diversity and bisection bandwidth between two nodes of a network, effectively quantifying the effect of policies on these metrics. Exact values can be obtained if certain conditions hold. The approach is based on regular languages and can be applied in a variety of use cases.

While downstream Web traffic has been studied in detail, upstream Web traffic has not received much attention yet. We argue that upstream traffic deserves the same or even higher attention since data flows towards Web servers generally entail privacy-relevant user information. Our aim is to understand where to and how much data users send to Web services. To this end, we examine HTTP(S) requests of two 24 hour traces recorded at a gateway of a campus network. As HTTP is highly repetitive, we introduce a scalable approach to remove redundant parts from upstream Web traffic, yielding an approximation of actual information flow. We identify thirteen classes of Web services covering up to 95% of all outgoing HTTP information. Our methodology further allows to quantify and compare the share of information different Web service classes receive. We find that advertisement and analytics services receive two times more information during Web browsing than all first party Web services together.

In this work, we propose utilizing the rich connectivity between IXPs and ISPs for inter-domain path stitching, supervised by centralized QoS brokers. In this context, we highlight a novel abstraction of the Internet topology, i.e., the inter-IXP multigraph composed of IXPs and paths crossing the domains of their shared member ISPs. This can potentially serve as a dense Internet-wide substrate for provisioning guaranteed end-to-end (e2e) services with high path diversity and global IPv4 address space reach. We thus map the IXP multigraph, evaluate its potential, and introduce a rich algorithmic framework for path stitching on such graph structures.

Abstract Privacy in the Web has become a major concern resulting in the popular use of various tools for blocking tracking services. Most of these tools rely on manually maintained blacklists, which need to be kept up-to-date to protect Web users’ privacy efficiently. It is challenging to keep pace with today’s quickly evolving advertisement and analytics landscape. In order to support blacklist maintainers with this task, we identify a set of Web traffic features for identifying privacyintrusive services. Based on these features, we develop an automatic approach that learns the properties of advertisement and analytics services listed by existing blacklists and proposes new services for inclusion on blacklists. We evaluate our technique on real traffic traces of a campus network and find in the order of 200 new privacy-intrusive Web services that are not listed by the most popular Firefox plug-in Adblock Plus. The proposed Web traffic features are easy to derive, allowing a distributed implementation of our approach.

Inter-domain routing is based on a fully decentralized model, where multiple Autonomous Systems (AS) interact via the BGP protocol. Although BGP is the "glue" of the Internet, it faces a lot of problems regarding its fully distributed nature, policy enforcement capabilities, scalability, security and complexity. Due to the widespread adoption of BGP, only incrementally deployable solutions are feasible. Taking this observation into account, we describe a new, backwards-compatible routing model which is based on outsourcing and logically centralizing the routing control plane. We claim that outsourcing enables enhanced inter-domain routing. As multiple ASes outsource their routing control plane to the same outsourcing service contractor, AS clusters are being gradually formed. A logically centralized multi-AS routing control platform based on Software Defined Networking (SDN) principles is the natural point for taking efficient routing decisions, detecting policy conflicts, troubleshooting routing problems, and evolving BGP. We present the technical and financial incentives which support the feasibility of the model and also propose an implementation scheme to facilitate it.

The largest IXPs carry on a daily basis traffic volumes in the petabyte range, similar to what some of the largest global ISPs reportedly handle. This little-known fact is due to a few hundreds of member ASes exchanging traffic with one another over the IXP's infrastructure. This paper reports on a first-of-its-kind and in-depth analysis of one of the largest IXPs worldwide based on nine months' worth of sFlow records collected at that IXP in 2011.

Recent studies show that a significant part of Internet traffic is delivered through Web-based applications. To cope with the increasing demand for Web content, large scale content hosting and delivery infrastructures, such as data-centers and content distribution networks, are continuously being deployed. Being able to identify and classify such hosting infrastructures is helpful not only to content producers, content providers, and ISPs, but also to the research community at large. For example, to quantify the degree of hosting infrastructure deployment in the Internet or the replication of Web content.

The Domain Name System (DNS) is a fundamental building block of the Internet. Today, the performance of more and more applications depend not only on the responsiveness of DNS, but also the exact answer returned by the queried DNS resolver, e. g., for Content Distribution Networks (CDN). In this paper, we compare local DNS resolvers against GoogleDNS and OpenDNS for a large set of vantage points. Our end-host measurements inside 50 commercial ISPs re-veal that two aspects have a significant impact on respon-siveness: (1) the latency to the DNS resolver, (2) the content of the DNS cache when the query is issued. We also observe significant diversity, even at the AS-level, among the answers provided by the studied DNS resolvers. We attribute this diversity to the location-awareness of CDNs as well as to the location of DNS resolvers that breaks the assumption made by CDNs about the vicinity of the end-user and its DNS resolver. Our findings pinpoint limitations within the DNS deployment of some ISPs, as well as the way third-party DNS resolvers bias DNS replies.

Content delivery systems constitute a major portion of today’s In-ternet traffic. While they are a good source of revenue for Internet Service Providers (ISPs), the huge volume of content delivery traf-fic also poses a significant burden and traffic engineering challenge for the ISP. The difficulty is due to the immense volume of trans-fers, while the traffic engineering challenge stems from the fact that most content delivery systems themselves utilize a distributed infrastructure. They perform their own traffic flow optimization and realize this using the DNS system. While content delivery sys-tems may, to some extent, consider the user’s performance within their optimization criteria, they currently have no incentive to con-sider any of the ISP’s constraints. As a consequence, the ISP has “lost control ” over a major part of its traffic. To overcome this im-pairment, we propose a solution where the ISP offers a Provider-aided Distance Information System (PaDIS). PaDIS uses informa-tion available only to the ISP to rank any client-host pair based on distance information, such as delay, bandwidth or number of hops. In this paper we show that the applicability of the system is sig-nificant. More than 70 % of the HTTP traffic of a major European ISP can be accessed via multiple different locations. Moreover, we show that deploying PaDIS is not only beneficial to ISPs, but also to users. Experiments with different content providers show that improvements in download times of up to a factor of four are possible. Furthermore, we describe a high performance implemen-tation of PaDIS and show how it can be deployed within an ISP.