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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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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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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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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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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

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