180 Park Ave - Building 103
Florham Park, NJ
Walter Willinger, a member of the Information and Software Systems Research Center at AT&T Labs Research in Florham Park, NJ, has been a leading researcher into the self-similar ("fractal") nature of Internet traffic. His paper "On the Self-Similar Nature of Ethernet Traffic" is featured in "The Best of the Best - Fifty Years of Communications and Networking Research," a 2007 IEEE Communications Society book compiling the most outstanding papers published in the communications and networking field in the last half century. More recently, he has focused on investigating the topological structure of the Internet and on developing a theoretical foundation for the study of large-scale communication networks such as the Internet.
SIAM Fellow, 2009.
For the study of network traffic and the internet.
AT&T Fellow, 2007.
Large data network behavior: Honored for fundamental contributions to understanding the behavior of large data networks.
ACM Fellow, 2005.
For contributions to the analysis of data networks and protocols.
IEEE Fellow, 2005.
For the analysis and mathematical modeling of Internet traffic.
Dasu: Pushing Experiments to the Internet's Edge
Mario A. Sanchez, John S. Otto, Zachary S. Bischof, David R. Choffnes, Fabian E. Bustamante, Balachander Krishnamurthy, Walter Willinger
Proceedings of 10th USENIX Symposium on Networked Systems Design and Implementation (NSDI'13),
2013.
[PDF]
[BIB]
{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, describe our current design and implementation, and illustrate the unique perspective it brings to Internet measurement. Dasu has been publicly available since July 2010 and has been installed by over 90,000 users with a heterogeneous set
of connections spreading across 1,802 networks and 147 countries.}
Spatio-Temporal Compressive Sensing and Internet Traffic Matrices (Extended Version)
University of Adelaide Matthew Roughan, Yin Zhang, Walter Willinger, Lili Qiu
IEEE/ACM Transactions on Networking,
2012.
[PDF]
[BIB]
IEEE Copyright
This version of the work is reprinted here with permission of IEEE for your personal use. Not for redistribution. The definitive version was published in IEEE/ACM Transactions on Networking. , Volume 20, Issue 3, 2012-06-01, 10.1109/TNET.2011.2169424
{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 when dealing with
real-world networks. In the case where such data have spatio-temporal
structure, it is natural to try to leverage this structure
to deal with the challenges posed by the problematic nature of the
data. Our work involving network datasets draws on ideas from
the area of compressive sensing and matrix completion, where
sparsity is exploited in estimating quantities of interest. However,
the standard results on compressive sensing are (i) reliant on
conditions which generally don�t hold for network datasets, and
(ii) don�t allow us to exploit all we know about their spatio-temporal
structure. In this paper we overcome these limitations
with an algorithm that has at its heart the same ideas espoused
in compressive sensing, but adapted to the problem of network
datasets. We show how this algorithm can be used in a variety
of ways, in particular on traffic data, to solve problems such as
simple interpolation of missing values, traffic matrix inference
from link data, prediction, and anomaly detection. The elegance
of the approach lies in the fact that it unifies all of these tasks,
and allows them to be performed even when as much as 98% of
the data is missing.}
Human Mobility Modeling at Metropolitan Scales
Sibren Isaacman, Richard Becker, Ramon Caceres, Margaret Martonosi, James Rowland, Alexander Varshavsky, Walter Willinger
10th ACM International Conference on Mobile Systems, Applications and Services (MobiSys 2012),
2012.
[PDF]
[BIB]
ACM Copyright
(c) ACM, 2012. This is the author's version of the work. It is posted here by permission of ACM for your personal use. Not for redistribution. The definitive version was published in [10th ACM International Conference on Mobile Systems, Applications and Services (MobiSys 2012)] , 2012-06-26.
{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 as Call Detail Records (CDRs) from a cellular telephone network, and produces synthetic CDRs for a synthetic population. We have validated WHERE against billions of anonymous location samples for hundreds of thousands of phones in the New York and Los Angeles metropolitan areas. We found that WHERE offers significantly higher fidelity than other modeling approaches. For example, daily range of travel statistics fall within one mile of their true values, an improvement of more than 14 times over a Weighted Random Waypoint model. Our modeling techniques and synthetic CDRs can be applied to a wide range of problems while avoiding many of the privacy concerns surround- ing real CDRs.}
Anatomy of a Large European IXP
Walter Willinger, ETH Zurich Bernhard Ager, TU Berlin/T-Labs Nikolaos Chatzis, TU Berlin/T-Labs Anja Feldmann, TU Berlin/T-Labs Nadi Sarrar, QMUL Steve Uhlig
Computer Communication Review (Proc. of the 2012 ACM Sigcomm Conference),
2012.
[PDF]
[BIB]
ACM Copyright
(c) ACM, 2012. This is the author's version of the work. It is posted here by permission of ACM for your personal use. Not for redistribution. The definitive version was published in 2012 , Volume 42, Issue 4, 2012-08-01, http://conferences.sigcomm.org/sigcomm/2012/.
{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 month worth of sFlow records collected at that IXP in 2011.
A main finding of our study is that the number of actual peering links at this single IXP exceeds the total number of AS links of the peer-peer type in the entire Internet known
as of 2010! To explain such a surprisingly rich peering fabric, we examine in detail this IXP�s ecosystem and highlight the diversity of networks that are members at this IXP and connect there with other member ASes for reasons that are similarly diverse, but can be partially inferred from their business types and observed traffic patterns. In the process, we investigate this IXP�s traffic matrix and illustrate what its temporal and structural properties can tell us about the member ASes that generated the traffic in the first place. While our results suggest that these large IXPs can be viewed as a
microcosm of the Internet ecosystem itself, they also argue for a re-assessment of the mental picture that our community has about this ecosystem.}
10 Lessons from 10 Years of Measuring and Modeling the Internet's Autonomous Systems
University of Adelaide Matthew Roughan, Walter Willinger, Loughborough University Olaf Maennel, Debbie Perouli, Randy Bush
IEEE Journal on Selected Areas in Communications (JSAC),
2012.
[PDF]
[BIB]
IEEE Copyright
This version of the work is reprinted here with permission of IEEE for your personal use. Not for redistribution. The definitive version was published in IEEE Journal on Selected Areas in Communications (JSAC), Special Issue on "Measurement of Inter. , Volume 29, Issue 9, 2012-08-01, 10.1109/JSAC.2011.111006
{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 inter-domain routing protocol.
The element of this inter-domain routing system that has attracted
the single-most attention within the research community has been the
``inter-domain topology''. Unfortunately, almost from the get go,
the vast majority of studies of this topology, from definition, to
measurement, to modeling and analysis, have ignored the central role
of BGP in this problem. The legacy is a set of specious findings,
unsubstantiated claims, and ill-conceived ideas about the Internet
as a whole.
By presenting a BGP-focused state-of-the-art treatment of the
aspects that are critical for a rigorous study of this inter-domain
topology, we de-mystify in this paper many ``controversial''
observations reported in the existing literature. At the same time,
we illustrate the benefits and richness of new scientific approaches
to measuring, modeling, and analyzing the inter-domain topology that
are faithful to the BGP-specific nature of this problem domain.}
Eyeball ASes: From Geography to Connectivity
Amir Rasti, Nazanin Magharei, Reza Rejaie, Walter Willinger
Proc. of the 2010 ACM Internet Measurement Conference (IMC '10),
IMC'10: Proceedings of the 2010 ACM Internet Measurement Conference (IMC),
2010.
[PDF]
[BIB]
ACM Copyright
(c) ACM, 2010. This is the author's version of the work. It is posted here by permission of ACM for your personal use. Not for redistribution. The definitive version was published in ACM Internet Measurement Conference , 2010-11-01, http://conferences.sigcomm.org/imc/2010/papers/p192.pdf
This paper presents a new approach to determine the geographical
footprint of individual eyeball Autonomous Systems
(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 to estimate the density of users across individual
eyeball ASes. This method enables us to cope with the error
associated with the location of end-users while controlling
the level of aggregation among data points to capture a geo-footprint
at the desired resolution. We use the resulting geo-footprint
of individual eyeball ASes to identify their likely
Point-of-Presence (PoP) locations. To demonstrate our proposed
technique, we use the inferred geo-locations of 48million
users from three popular P2P applications and assess
the geo- and PoP-level footprints of 1229 eyeball ASes. The
validation of the identified PoP locations by our technique
against online information and prior results by a commonly-used
technique based on traceroute shows a very high accuracy.
Leveraging the acquired PoP locations, we examine the
implications of geo-footprint of eyeball ASes on their connectivity
to the rest of the Internet. In particular, we present
a case study that reveals a much more complex picture of
AS-level connectivity as compared to what the more traditional
but geography-agnostic BGP- or traceroute-based approaches
show.
TCP Revisited: A Fresh Look at TCP in the Wild
Feng Qian, Alexandre Gerber, Z. Morley Mao, Subhabrata Sen, Oliver Spatscheck, Walter Willinger
in Proc. of ACM Internet Measurement Conference (IMC),
2009.
[PDF]
[BIB]
ACM Copyright
(c) ACM, 2009. This is the author's version of the work. It is posted here by permission of ACM for your personal use. Not for redistribution. The definitive version was published in ACM Internet Measurement Conference, 2009-11-04
{Since the last in-depth studies of measured TCP traffic some 6-
8 years ago, the Internet has experienced significant changes, including
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 changes beg the question whether the
characteristics of measured TCP traffic in today�s Internet reflect
these changes or have largely remained the same. To answer this
question, we collected and analyzed packet traces from a number of
Internet backbone and access links, focused on the �heavy-hitter�
flows responsible for the majority of traffic. Next we analyzed their
within-flow packet dynamics, and observed the following features:
(1) in one of our datasets, up to 15.8% of flows have an initial congestion
window (ICW) size larger than the upper bound specified
by RFC 3390. (2) Among flows that encounter retransmission rates
of more than 10%, 5% of them exhibit irregular retransmission behavior
where the sender does not slow down its sending rate during
retransmissions. (3) TCP flow clocking (i.e., regular spacing between
flights of packets) can be caused by both RTT and non-RTT
factors such as application or link layer, and 60% of flows studied
show no pronounced flow clocking. To arrive at these findings,
we developed novel techniques for analyzing unidirectional TCP
flows, including a technique for inferring ICW size, a method for
detecting irregular retransmissions, and a new approach for accurately
extracting flow clocks.}
Reverse Engineering Peering At Internet Exchange Points,
Tue Mar 29 16:02:00 EDT 2011
A technique for examining the relationships of autonomous systems (ASes) participating in an Internet Exchange Point (IXP) utilizes packet tracing servers proximate the IXPs. Where such packet tracing servers cannot be found in the participating ASes, the methodology identifies additional vantage points by looking at a list of ASes that are one hop away from the ASes at the IXP. The choice of one-hop away ASes is made judiciously by picking ones that have better connectivity, based on past-data. Plural-hop ASes may also be used where necessary.
