Walter Willinger's research while affiliated with Princeton University and other places

Publications (219)

Article
The application of machine learning (ML) to mitigate network-related problems poses significant challenges for researchers and operators alike. For one, there is a general lack of labeled training data in networking, and labeling techniques popular in other domains are ill-suited due to the scarcity of operators’ domain expertise. Second, network p...
Article
The main premise of this work is that since large cloud providers can and do manipulate probe packets that traverse their privately owned and operated backbones, standard traceroute-based measurement techniques are no longer a reliable means for assessing network connectivity in large cloud provider infrastructures. In response to these development...
Article
The main premise of this work is that since large cloud providers can and do manipulate probe packets that traverse their privately owned and operated backbones, standard traceroute-based measurement techniques are no longer a reliable means for assessing network connectivity in large cloud provider infrastructures. In response to these development...
Article
Applications based on the compute-in-the-network (COIN) paradigm require flexible network telemetry data to drive effective allocation decisions. Telemetry systems collect such data based on queries specifying the precise traffic metrics or features required. Recent advances in programmable switch hardware have led to highly efficient methods to co...
Preprint
The emergence of programmable data-plane targets has motivated a new hybrid design for network streaming analytics systems that combine these targets' fast packet processing speeds with the rich compute resources available at modern stream processors. However, these systems require careful query planning; that is, specifying the minute details of e...
Article
Full-text available
The most-followed Twitter users and their pairwise relationships form a subgraph of Twitter users that we call the Twitter elite network. The connectivity patterns and information exchanges (in terms of replies and retweets) among these elite users illustrate how the “important” users connect and interact with one another on Twitter. At the same ti...
Chapter
Today’s enterprises are adopting multi-cloud strategies at an unprecedented pace. Here, a multi-cloud strategy specifies end-to-end connectivity between the multiple cloud providers (CPs) that an enterprise relies on to run its business. This adoption is fueled by the rapid build-out of global-scale private backbones by the large CPs, a rich privat...
Conference Paper
Full-text available
A growing concern within today's networking community is that with the proliferation of Artificial Intelligence/Machine Learning (AI/ML) techniques, a lack of access to real-world production networks is putting academic researchers at a significant disadvantage. Indeed, compared to a select few research groups in industry that can leverage access t...
Article
This editorial is an outgrowth of our research efforts that resulted in the SIGCOMM'93 paper [1] entitled On the self-similar nature of Ethernet traffic. We discuss some lessons we have learned as we have watched the published findings being absorbed by the scientific community in general and the networking community in particular. We focus on aspe...
Article
Our main purpose for this editorial is to reiterate the main message that we tried to convey in our SIGCOMM'04 paper but that got largely lost in all the hype surrounding the use of scale-free network models throughout the sciences in the last two decades. That message was that because of (1) the Internet's highly-engineered architecture, (2) a tho...
Conference Paper
The growing demand for an ever-increasing number of cloud services is profoundly transforming the Internet's interconnection or peering ecosystem, and one example is the emergence of "virtual private interconnections (VPIs)". However, due to the underlying technologies, these VPIs are not publicly visible and traffic traversing them remains largely...
Article
Internet interconnections are the means by which networks exchange traffic between one another. These interconnections are typically established in facilities that have known geographic locations, and are owned and operated by so-called colocation and interconnection services providers (e.g., Equinix, CoreSite, and EdgeConneX). These previously und...
Conference Paper
Today's large content providers (CP) are busy building out their service infrastructures or "peering edges" to satisfy the insatiable demand for content created by an ever-expanding Internet edge. One component of these serving infrastructures that features prominently in this build-out is their connectivity fabric; i.e., the set of all Internet in...
Conference Paper
Managing and securing networks requires collecting and analyzing network traffic data in real time. Existing telemetry systems do not allow operators to express the range of queries needed to perform management or scale to large traffic volumes and rates. We present Sonata, an expressive and scalable telemetry system that coordinates joint collecti...
Preprint
Full-text available
Access to fiber-optic connectivity in the Internet is traditionally offered either via lit circuits or dark fiber. Economic (capex vs. opex) and operational considerations (latency, capacity) dictate the choice between these two offerings, but neither may effectively address the specific needs of modern-day enterprises or service providers over a r...
Article
Operating networks depends on collecting and analyzing measurement data. Current technologies do not make it easy to do so, typically because they separate data collection (e.g., packet capture or flow monitoring) from analysis, producing either too much data to answer a general question or too little data to answer a detailed question. In this pap...
Conference Paper
Full-text available
Programmable switches potentially make it easier to perform flexible network monitoring queries at line rate, and scalable stream processors make it possible to fuse data streams to answer more sophisticated queries about the network in real-time. However, processing such network monitoring queries at high traffic rates requires both the switches a...
Article
Analyzing and modeling social network dynamics are key to accurately predicting resource needs and system behavior in online social networks. The presence of statistical scaling properties, that is, self-similarity, is critical for determining how to model network dynamics. In this work, we study the role that self-similarity scaling plays in a soc...
Article
The complexity and enormous costs of installing new long-haul fiber-optic infrastructure has led to a significant amount of infrastructure sharing in previously installed conduits. In this paper, we study the characteristics and implications of infrastructure sharing by analyzing the long-haul fiber-optic network in the US. We start by using fiber...
Conference Paper
The risk of placing an undesired load on networks and networked services through probes originating from measurement platforms has always been present. While several scheduling schemes have been proposed to avoid undue loads or DDoS-like effects from uncontrolled experiments, the motivation scenarios for such schemes have generally been considered...
Article
Capturing an accurate view of the Internet topology is of great interest to the networking research community as it has many uses ranging from the design and evaluation of new protocols and services to the vulnerability analysis of the network's infrastructure. However, the scale of today's Internet coupled with its distributed and heterogeneous na...
Conference Paper
As the Internet continues to grow both in size and in terms of the volume of traffic it carries, more and more networks in the different parts of the world are relying on an increasing number of distinct ways to exchange traffic with one another. As a result, simple questions such as “What is the application mix in today’s Internet?” may produce no...
Article
The recently launched initiative by the Open-IX Association (OIX) to establish the European-style Internet eXchange Point (IXP) model in the US suggests an intriguing strategy to tackle a problem that some Internet stakeholders in the US consider to be detrimental to their business; i.e., a lack of diversity in available peering opportunities. We e...
Article
Characterizing the flow of Internet traffic is important in a wide range of contexts, from network engineering and application design to understanding the network impact of consumer demand and business relationships. Despite the growing interest, the nearly impossible task of collecting large-scale, Internet-wide traffic data has severely constrain...
Article
During the last few years, more and more of the medium-to-large Internet eXchange Points (IXP) around the world have started to operate a route server and offer its use as a free value-added service to their members. This service has greatly simplified inter-domain routing for those members and has made it easy for them to peer with possibly hundre...
Article
This paper presents a simple framework, called WalkAbout, to infer a coarse view of connectivity in very large graphs; that is, identify well-connected "regions" with different edge densities and determine the corresponding inter- and intra-region connectivity. We leverage the transient behavior of many short random walks (RW) on a large graph that...
Conference Paper
Recent Internet studies have reported on continued traffic growth, changes in applications usage, and a proliferation in the adoption of high-speed access links. Any adverse impact that these observed trends may have on Internet traffic flows can result in sub par performance, which in turn results in unsatisfactory user experience. To study such a...
Article
Full-text available
Poor visibility into the network hampers progress in a number of important research areas, from network troubleshooting to Internet topology and performance mapping. This persistent, well-known problem has served as motivation for numerous proposals to build or extend existing Internet measurement platforms by recruiting larger, more diverse vantag...
Article
The large volume of data associated with social networks hinders the unaided user from interpreting network content in real time. This problem is compounded by the fact that there are limited tools available for enabling robust visual social network ...
Article
Many Internet mapping projects have used traceroute as a measurement primitive and have generated hundreds of millions of traceroute samples used, among many purposes, for network debugging, troubleshooting and Internet mapping. In this work, we advocate the use of visualization as a means to extract semantics from large sets of traceroute data col...
Article
Full-text available
Internet eXchange Points (IXPs) are generally considered to be the successors of the four Network Access Points (NAPs) that were mandated as part of the decommissioning of the National Science Foundation Network (NSFNET) in 1994/95 to facilitate the transition from the NSFNET to the "public Internet" as we know it today. While this popular view doe...
Patent
Full-text available
Certain exemplary embodiments can provide a method, which can comprise, based upon a quantified completeness of a determined topology of an interconnected set of Autonomous Systems of the Internet, at a user interface of an information device, automatically rendering a determined identity of a customer to which telecommunications products will be o...
Conference Paper
We present Dasu, a measurement experimentation platform for the Internet's edge. Dasu supports both controlled network experimentation and broadband characterization, building on public interest on the latter to gain the adoption necessary for the former. We discuss some of the challenges we faced building a platform for the Internet's edge, descri...
Article
Full-text available
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...
Article
Full-text available
Models of human mobility have broad applicability in fields such as mobile computing, urban planning, and ecology. This paper proposes and evaluates WHERE, a novel approach to modeling how large populations move within different metropolitan areas. WHERE takes as input spatial and temporal probability distributions drawn from empirical data, such a...
Article
Despite advances in measurement technology, it is still challenging to reliably compile large-scale network datasets. For example, because of flaws in the measurement systems or difficulties posed by the measurement problem itself, missing, ambiguous, or indirect data are common. In the case where such data have spatio-temporal structure, it is nat...
Article
Traditional queueing models for traffic flows in communications networks are based on Markovian assumptions. However, recent studies within Bellcore of large sets of real-time network traffic measurements have revealed that traffic in computer and emerging high-speed networks has features that are more accurately and more efficiently described in t...
Article
Formally, the Internet inter-domain routing system is a collection of networks, their policies, peering relationships and organizational affiliations, and the addresses they advertize. It also includes components like Internet exchange points. By its very definition, each and every aspect of this system is impacted by BGP, the de-facto standard int...
Article
Full-text available
The 11 papers in this special issue (i) highlight the multi-faceted nature of connectivity or graph structures that are supported by today's Internet, (ii) illustrate the benefits and richness of principled approaches to measuring, modeling, and analyzing the resulting graph structures in ways that respect their layer-specific nature, and (iii) dem...
Article
Nearly three decades of Internet measurement has resulted in large-scale global infrastructures used by an increasing number of researchers. They have examined various Internet properties in areas such as network infrastructure (routers, links), traffic (measurement at packet, flow, and session level) and applications (DNS, Web, P2P, Online Social...
Conference Paper
An understanding of Internet topology is central to answer various questions ranging from network resilience to peer selection or data center location. While much of prior work has examined AS-level connectivity, meaningful and relevant results from such an abstract view of Internet topology have been limited. For one, semantically, AS relationship...
Conference Paper
This paper presents a new approach to determine the geographical footprint of individual Autonomous Systems that directly provide service to end-users, i.e., eyeball ASes. The key idea is to leverage the geo-location of end-users associated with an eyeball AS to identify its geographical footprint. We leverage the kernel density estimation method t...
Article
While the size of popular online social networks such as MySpace and Twitter has been reported to be in the tens or hundreds of millions of users (and growing), little is known about the fraction of users who have either deleted or abandoned their accounts. Therefore, the growth of an OSN's overall user population and, more important, its populatio...
Article
Online Social Networks (OSNs) have been the subject of a great deal of study in recent years. The majority of this study has used simple models, such as node-and-edge graphs, to describe the data. In this paper, we argue that such models, which necessarily limit the structures that can be described and omit temporal information, are insufficient to...
Conference Paper
This paper examines the problem of characterizing and as- sessing the global impact of the load imposed by a Peer-to-Peer (P2P) overlay on the AS-level underlay. In particular, we capture Gnutella snap- shots for four consecutive years, obtain the corresponding AS-level topol- ogy snapshots of the Internet and infer the AS-paths associated with eac...
Conference Paper
Empirical analysis and mathematical modeling have been the foundation for a great deal of network research and have resulted in significant improvements to Internet systems, protocols and practices. Recent progress applying a constantly expanding set of sophisticated statistical tools and mathematical techniques suggests the emergence of a new type...
Article
Full-text available
Despite significant efforts to obtain an accurate picture of structure at the level of individual autonomous systems (ASes), much remains unknown in terms of the quality of the in- ferred AS maps that have been widely used by the research community. Building upon our recent results reported in (16), in this paper we take a first step towards quanti...
Conference Paper
Internet exchange points (IXPs) are an important ingredient of the Internet AS-level ecosystem - a logical fabric of the Internet made up of about 30,000 ASes and their mutual business relationships whose primary purpose is to control and manage the flow of traffic. Despite the IXPs' critical role in this fabric, little is known about them in terms...
Conference Paper
Since the last in-depth studies of measured TCP traffic some 6 - 8 years ago, the Internet has experienced significant change s, in- cluding the rapid deployment of backbone links with 1-2 orders of magnitude more capacity, the emergence of bandwidth-intensive streaming applications, and the massive penetration of new TCP variants. These and other...
Conference Paper
Full-text available
Online Social Networks (OSNs) have already attracted more than half a billion users. However, our understanding of which OSN fea- tures attract and keep the attention of these users is poor. S tudies thus far have relied on surveys or interviews of OSN users or fo- cused on static properties, e. g., the friendship graph, gat hered via sampled crawl...
Conference Paper
While some empirical studies on Online Social Networks (OSNs) have examined the growth of these systems, little is known about the patterns of decline in user population or user activity (in terms of visiting their OSN account) in large OSNs, mainly because capturing the required information is challenging. In this paper, we examine the evolution o...
Conference Paper
Most of the existing literature on empirical studies of Online Social Networks (OSNs) have focused on characterizing and modeling the structure of their inferred friendship graphs. However, the friendship graph of an OSN does not demon- strate what fraction of its users actively interact with other users, how these users interact, and how these act...
Conference Paper
Full-text available
Many basic network engineering tasks (e.g., traffic engineering, capacity planning, anomaly detection) rely heavily on the availability and accuracy of traffic matrices. However, in practice it is challenging to reliably measure traffic matrices. Missing values are common. This observation brings us into the realm of compressive sensing, a generic...
Conference Paper
This paper presents Respondent-Driven Sampling (RDS) as a promising technique to derive unbiased estimates of node properties in unstructured overlay networks such as Gnutella. Using RDS and a previously proposed technique, namely Metropolized Random Walk (MRW) sampling, we examine the efficiency of estimating node properties in unstructured overla...
Article
Full-text available
Graph theory models the Internet mathematically, and a number of plausible mathematically intersecting network models for the Internet have been developed and studied. Simultaneously, Internet researchers have developed methodology to use real data to validate, or invalidate, proposed Internet models. The authors look at these parallel developments...
Article
This paper presents a detailed examination of how the dynamic and heterogeneous nature of real-world peer-to-peer systems can introduce bias into the selection of representative samples of peer properties (e.g., degree, link bandwidth, number of files shared). We propose the Metropolized Random Walk with Backtracking (MRWB) as a viable and promisin...
Article
Full-text available
Online Social Networks (OSNs) provide a unique opportunity for researchers to study how a combination of technological, economical, and social forces have been conspiring to provide a service that has attracted the largest user population in the history of the Internet. With more than half a billion of users and counting, OSNs have the potential to...
Article
Network monitoring is essential to the correct and efficient operation of ISP networks and the kind of applications they support, and active measurement is a key design problem in network monitoring. Unfortunately, almost all active probing algorithms ...
Conference Paper
Full-text available
Most research on tra-c matrices (TM) has focused on flnd- ing models that help with inference, but not with other im- portant tasks such as synthesis of TMs, tra-c prediction, or anomaly detection. In this paper we approach the problem of a general model for tra-c matrices, and argue that such a model must be sparse, i.e., have a small number of pa...
Article
Despite significant efforts to obtain an accurate picture of the Internet's actual connectivity structure at the level of individual autonomous systems (ASes), much has remained unknown in terms of the quality of the inferred AS maps that have been widely used by the research community. In this paper we assess the quality of the inferred Internet m...
Article
Full-text available
The six articles in this issue focus on the properties and evolution of Internet scalability. The papers are summarized here.
Article
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In this paper, we discuss recent work on buffer sizing in the context of an ISP's need to offer and guarantee competitive Service Level Agreements (SLAs) to its customers. Since SLAs specify the per- formance that an ISP guarantees to its customers, they provide crit- ical context for many configuration and provisioning decisions and have specific...
Article
Full-text available
Traditional Internet traffic studies have primarily focused on the temporal characteristics of packet traces as observed on a single link within an ISP’s network. They have contributed to advances in the areas of self-similar stochastic processes, long-range dependence, and heavy-tailed distributions and have demonstrated the benefits of applying a...
Conference Paper
Full-text available
Despite significant efforts to obtain an accurate picture of the In- ternet's actual connectivity structure at the level of individual au- tonomous systems (ASes), much has remained unknown in terms of the quality of the inferred AS maps that have been widely used by the research community. In this paper we assess the quality of the inferred Intern...
Conference Paper
Critical network management applications increasingly demand fine-grained flow level measurements. How- ever, current flow monitoring solutions are inadequate for many of these applications. In this paper, we present the design, implementation, and evaluation of CSAMP, a system-wide approach for flow monitoring. The de- sign of CSAMP derives from t...
Article
Examining the validity or accuracy of proposed available bandwidth estimation tools remains a challenging problem. A common approach consists of evaluating a newly developed tool using a combination of simple ns-type simulations and feasible experiments in situ (i.e., using parts of the actual Internet). In this paper, we argue that this strategy t...
Article
Internet topology analysis has recently experienced a surge of interest in computer science, physics, and the mathematical sciences. However, researchers from these different disciplines tend to approach the same problem from different angles. As a result, the field of Internet topology analysis and modeling must untangle sets of inconsistent findi...
Conference Paper
During the past few years, Peer-to-Peer (P2P) applications have become increasingly popular over the Internet. In these applications, a large number (e.g., millions) of geographically distributed end-systems (or peers) form an overlay to exchange content and share their resources. Several recent studies have observed the network traffic at one or f...
Article
Full-text available
The Internet's layered architecture and organizational structure give rise to a number of different topologies, with the lower layers defining more physical and the higher layers more virtual/logical types of connectivity structures. These structures are very dif-ferent, and successful Internet topology modeling requires annotating the nodes and ed...
Chapter
A stochastic approximation technique is developed so that an Rd-valued random process X in discrete or continuous time can be viewed as a limit of "simple" quantities (ξ(n)) (n≥0), subsequently called "skeletons". The important feature of the approximation is that convergence is understood in the strongest possible sense, not only for the processes...
Conference Paper
Peer-to-peer systems are becoming increasingly popular, with millions of simultaneous users and a wide range of applications. Understanding existing systems and devising new peer-to-peer techniques relies on access to representative models derived from empirical observations. Due to the large and dynamic nature of these systems, directly capturing...
Conference Paper
Compared to other large-scale, complex systems, one of the most appealing features of the Internet is that a thorough understanding of its component technologies combined with a unique ability to measure the network means that most of the models and theories proposed for explaining the Internet's observed structure and behavior can be in general un...
Conference Paper
Internet connectivity at the AS level, defined in terms of pairwise logical peering relationships, is constantly evolving. This evolution is largely a response to economic, political, and technological changes that impact the way ASs conduct their business. We present a new framework for modeling this evolutionary process by identifying a set of cr...
Conference Paper
Examining the validity or accuracy of proposed available bandwidth estimation tools remains a challenging problem. A common approach consists of evaluating a newly developed tool using a combination of simple nstype simulations and feasible experiments in situ (i.e., using parts of the actual Internet). In this paper, we argue that this strategy te...
Article
Full-text available
Building on a recent effort that combines a first-principles approach to modeling router-level connectivity with a more pragmatic use of statistics and graph theory, we show in this paper that for the Internet, an improved understanding of its physical infrastructure is possible by viewing the physical connectivity as an annotated graph that delive...
Article
Full-text available
Over the last decade there has been significant interest and attention devoted towards understanding the complex structure of the Internet, particularly its topology and the large-scale properties that can be derived from it. While recent work by empiricists and theoreticians has emphasized certain statistical and mathematical properties of network...
Article
Full-text available
The search for unifying properties of complex networks is popular, challenging, and important. For modeling approaches that focus on robustness and fragility as unifying concepts, the Internet is an especially attractive case study, mainly because its applications are ubiquitous and pervasive, and widely available expositions exist at every level o...
Article
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This article examines contrasting notions of self-organization in the Internet and next-generation communication networks, by reviewing in some detail recent evidence regarding several of the more popular attempts to explain prominent features of Internet structure and behavior as "emergent phenomena." In these examples, what might appear to the no...