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Measuring the Spatial Structure of Traffic Congestion in the Internet
Gábor Vattay
Center for Communication Networks Data Analysis, Collegium Budapest
Physics of Complex Systems, Eötvös University
ELTE-Ericsson Research Communication Networks Laboratory
Spatial Structure of Internet Traffic
The Blue Ocean • Telecommunication Services and Computer Hardware
Equipment is one of the most R&D intensive sectors (70 B$ R&D spending in 2005)
• Research spending traditionally goes into Electrical Engineering and Computer Science, Physics,
Complexity is not on the horizon due to cultural problems
• While in biology, economy/finance there is traditional scientific competition, telecommunication is still a competition free Blue Ocean for complexity research
• Interdisciplinary research of Engineering and Complex Systems has a great perspective if log-logging is avoided
Inspiration from complex system side: What you need?
Complex NetworkSelfsimilar Traffic
Nonlinearity and Chaos
Spatial Structure of Internet Traffic
Topology
Spatial Structure of Internet Traffic
The Faloutsos Graph 1999
Spatial Structure of Internet Traffic
Traffic
Spatial Structure of Internet Traffic
Typical internet traffic traces
W. E. Leland et al. SIGCOMM 93
Spatial Structure of Internet Traffic
Chaos
Spatial Structure of Internet Traffic
Chaos in Computer Networks
Spatial Structure of Internet Traffic
Periodicity
Veres & Boda INFOCOM 2000
Spatial Structure of Internet Traffic
Chaos
Veres & Boda INFOCOM 2000
Spatial Structure of Internet Traffic
Ljapunov properties
Veres & Boda INFOCOM 2000
Spatial Structure of Internet Traffic
Strange attractor
Veres & Boda INFOCOM 2000
Spatial Structure of Internet Traffic
Active Internetmeasurements
• Internet: highly heterogeneous and decentralized
• why are we measuring state variables (e.g. loss-rates, delays, bandwith)?– to predict the quality of various services and applications over the
Internet,– to construct more efficient transfer protocols,– to analyze the spatial structure of the traffic, etc.
• active probing:– injecting probe packets + analyzing the received probe stream– end-to-end information about the participating nodes– resolved information: only with the cooperation of routers
Spatial Structure of Internet Traffic
Network Tomography
Method: we send back-to-back packet pairs and measure their end-to-end delay at arrival with very high precision
Goal: to resolve delay statistics on internal network segments too, where we do not have monitoring stations
Key idea: delay correlation on the common segment for the packets in a pair
Spatial Structure of Internet Traffic
Delay estimation for
the Y-topology Definitions:• N - number of successful pairs, where none of the probes is lost.• and , the end-to-end delay experienced by the
probes of the k-th pair
• Goal: Estimate the distribution of , and
from the end-to-end delays.
• Quantization of the delay into B bins of uniform size q
if ,
)(2 kY
)()()( 211 kXkXkY )()()( 312 kXkXkY Nk ..1
)(1 kX )(2 kX )(3 kX
)(1 kY
jqkX di )( jqkXqj i )()1( Bji ,..2,13,2,1
Spatial Structure of Internet Traffic
B
j ji
ji
n
n
jiP1 ,
,
,
)()()( 211 kXkXkY ddd
)()()( 312 kXkXkY ddd
1)(1)(1
)(,3)(,2,1
21
),(
),(
smBslBsBH
smslHs
s
dd
PPPmlP
mqYlqYP
))(),(( 211
nYnYPL ddN
n
Spatial Structure of Internet Traffic
EM-algorithm
B
j ji
ji
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n
jiP1 ,
,
,
),(),|(
),(),|(
),(),|(
,3)(,2)(,13
)(,3,2)(,12
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))(),(|)(( 211
, mYkYjqkXPn dddi
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kji
0, jiP
Spatial Structure of Internet Traffic
msX 1832 msX 2283
msX 1751
Spatial Structure of Internet Traffic
Real and virtual measurement
points
The etomic active probing infrastructure
Spatial Structure of Internet Traffic Best Testbed Award
• The European Traffic Observatory Measurement InfrastruCture (etomic) was created in 2004-05 within the Evergrow Integrated Project launched by the Future and Emergent Technologies Programme of the European Union.
• Its goals:– to provide an open access, public test bed for
researchers investigating the Internet with active measurement methods
– to serve as a Virtual Observatory active measurement data on the European part of the Internet
History
Spatial Structure of Internet Traffic
Founders• Its Central Management System (CMS) has been
developed by the Grupo de Redes, Sistemas y Servicios Telemáticos Departamento de Automática y Computación Universidad Pública de Navarra.
• Its hardware infrastructure has been designed and built by the Cooperative Center for Communication Network Data Analysis in Collegium Budapest Institute for Advanced Study.
• The measurement stations are hosted by European research groups collaborating in the Evergrow project.
Spatial Structure of Internet Traffic
Measurement sites
Spatial Structure of Internet Traffic
Visualization
2005.07.01. 3:30AM
Spatial Structure of Internet Traffic
Visualization
2005.07.01. 3:30AM
Spatial Structure of Internet Traffic
Topology of routers
etomic stationsrouters
Spatial Structure of Internet Traffic
Snapshot of queueing dealys in Europe
Spatial Structure of Internet Traffic
Daily change of mean queuing delays
Spatial Structure of Internet Traffic
Distribution of the mean queuing delay
(night 3:30)
Spatial Structure of Internet Traffic
Distribution of the mean queuing delay
(afternoon 16:00)
Spatial Structure of Internet Traffic
Distribution of the mean queuing delay
(day 14:00)
Variance vs. mean
Day
Night
Afternoon
Spatial Structure of Internet Traffic
Main results
Log-normal distribution of the delay Variance and delay are proportional
Future measuremnets
Spatial Structure of Internet Traffic
Growing number of monitored links
Spatial Structure of Internet Traffic
The DIMES project
Spatial Structure of Internet Traffic
DIMES Agents in Europe
Spatial Structure of Internet Traffic
Measurement sites
Properly located Dimes agents (red)Branching routers (blue)
Spatial Structure of Internet Traffic
Expectations 2.
Number of Dimes agents
Num
ber
of d
isco
vere
dse
gmen
ts/b
ranc
hing
rou
ters
Newly discovered internal segments
Newly discovered branching routers
Traceroute between 257 Dimes agents and 15 Etomic nodes
Spatial Structure of Internet Traffic
Thanks!
IST Future and Emerging Technologies
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