정하경 mmlab fundamentals of internet measurement: a tutorial nevil brownlee, chris lossley,...
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정하경
MMLAB
Fundamentals of Internet Fundamentals of Internet Measurement: a TutorialMeasurement: a Tutorial
Nevil Brownlee, Chris Lossley, “Fundamentals of Internet Measurement: a Tutorial,” CMG journal of Computer Resource Management, Is
sue 102, Spring 2001
2006.12.04Presenter: Jung, Hakyung
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MMLAB OutlineOutline
Motivation Measurement topics
H/W versus S/W approaches Active versus Passive measurements Examples
Main observations in the past research Conclusion
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MMLAB MotivationMotivation
Network troubleshooting Protocol debugging
Test out “new, improved” version of network applications and protocols
Workload characterization design of better protocols and network for supporting the
application
Performance evaluation and improvement Identifying performance bottleneck
• New versions of the protocols can provide better performance
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MMLAB Measurement TopicsMeasurement Topics
Hardware approaches Special-purpose tools designed to collect and analyze netw
ork data• Often expensive
• Better functionality and performance
Software approaches Modify the kernel for the packet-capture capability
• e.g. tcpdump
Access logs recorded by Web servers or proxies
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MMLABSoftware approach example:Software approach example:MIPv6 traffic measurementMIPv6 traffic measurement
HA
IPv6 Network
AP
IPFIX Flow Collector
MIPv6 Access Routerwith IPFIX
IPFIX flow data
IPv6 Router
MN
CN
FA FA
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MMLAB Measurement TopicsMeasurement Topics
Passive measurements Observe normal network traffic without creating additional tr
affic• e.g. counting # of packets traveling through routers
Do not perturb the network Rely on traffic flowing across the link being measured
Active measurements Send test traffic needed to make the measurement
• e.g. ping, traceroute utilities Generate extra traffic onto a network, thereby affecting mea
surement results
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MMLABPassive techniques:Passive techniques:
workload analysis (1/3)workload analysis (1/3)
A matrix of traffic from source to destination ASes 2 minute sample from FIX-
west in April 1998 can be used to optimize to
pology or to determine the traffic balance among ISPs
since AS is the unit of routing relationship
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MMLABPassive techniques:Passive techniques:
workload analysis (2/3)workload analysis (2/3)
A matrix of traffic from source to destination countries 2 minute sample from FIX-
west in April 1998 gives a perspective on
international commerce
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MMLABPassive techniques:Passive techniques:
workload analysis (3/3)workload analysis (3/3)
Cumulative distribution of packet sizes, and of bytes by the size of packets carrying them peaks at sizes of 44, 552,
576, and 1500 bytes
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MMLABActive technique:Active technique:
Internet mapping projectInternet mapping project
skitter, a tool for dynamically discovering and depicting global Internet topology uses the same procedures
with traceroute utility gathers connectivity inform
ation, RTT, path data
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MMLABActive technique:Active technique:
RTTs measurementRTTs measurement
The distribution of RTTs for 1600 probe packets nearly symmetric & relative
ly large distribution
The plot of delay values measured along the path congestion between
hop 11 and hop 12
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MMLABObservations in the past Observations in the past
research (1/3)research (1/3)
Packet traffic is non-uniformly distributed 10% of the hosts account for 90% of the traffic Client-Server paradigm
Network traffic exhibits “locality” properties Packets are not independent; rather part of a higher-layer
logical flow of information Temporal locality (time-based correlation) Spatial locality (geography-based correlation)
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MMLABObservations in the past Observations in the past
research (2/3)research (2/3)
The packet arrival process is not Poisson Poisson arrival process
• Events occur independently at random times• Inter-arrival times between events are exponentially distributed
and independent• Memoryless property
Inter-arrival times between packets are not exponentially distributed, nor are they independent
Packet arrival process is bursty
The session arrival process is Poisson Users seen to operate independently at random
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MMLABObservations in the past Observations in the past
research (3/3)research (3/3)
Traffic flows are bi-directional, but often asymmetric Download-intensive nature of the Web
Internet traffic continues to change Traffic volume, traffic mix, protocols, applications, users Data set collected from an operational network represents
bye one snapshot at one point in time in the evolution of the Internet
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MMLAB ConclusionConclusion
Role of network traffic measurement Design, testing, evaluation of Internet protocols &
applications
Internet traffic measurement Methodology
Summary of the main observations from the past network measurement research Internet traffic continues to change
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MMLAB ReferenceReference
N. Brownlee, C. Lossley, “Fundamentals of Internet Measurement: a Tutorial,” CMG journal of Computer Resource Management, Issue 102, Spring 2001
KC Claffy, “Internet measurement and data analysis:
passive and active measurement,” NAE workshop, 1999 C. Williamson, “Internet Traffic Measurement, “ IEEE Internet C
omputing, Vol. 5, No. 6, 2001 http://www.cybergeography.org/atlas/topology.html