Internet DRAFT - draft-peng-p2p-measurement
draft-peng-p2p-measurement
P2PRG Jin.Peng
Internet Draft China Mobile
Intended status: Informational Lifeng.Le
Expires: September 2012 China Mobile
Shihui.Duan
China CATR
March 12, 2012
Measurement for P2P system
draft-peng-p2p-measurement-00.txt
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Abstract
This document introduces general measurement research for p2p systems.
In this document, it first gives the objects for measurement in p2p
network, gives the methodology for p2p measurement and then describes
the material measurement indexed for p2p network.
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Table of Contents
1. Introduction ................................................ 4
2. P2p measurement content overview ............................. 4
3. P2p measurement methods ...................................... 4
3.1. Active measurement method ............................... 5
3.2. Passive measurement method .............................. 5
4. The measurement indexes for p2p network ...................... 5
4.1. p2p topology characteristics measurement ................ 5
4.1.1. Graph property measurement ......................... 6
4.1.2. Dynamic property measurement ....................... 6
4.2. p2p traffic characteristics measurement ................. 6
4.2.1. space characteristics measurement .................. 7
4.2.2. time characteristics measurement ................... 7
4.3. p2p availability characteristics measurement ............ 7
4.3.1. host availability measurement ...................... 7
4.3.2. content availability measurement ................... 7
5. Future work ................................................. 8
6. Acknowledgements ............................................ 8
7. Security Considerations ...................................... 8
8. IANA Considerations ......................................... 8
9. References .................................................. 8
9.1. Normative References .................................... 8
9.2. Informative References .................................. 8
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1. Introduction
With the progress of peer-to-peer (P2P) technology, the Internet
applications model is in a great reformation. In order to get an all-
win solution among the Internet users, Internet service providers and
content providers, it is necessary to measure and analyze the P2P
applications from their perspectives.
Measuring and characterizing the properties of p2p networks will
benefit the optimization, management of the p2p systems. It seems
infeasible to capture a complete and precise snapshot of p2p overlay
networks due to the variety of p2p protocols and dynamics of the
servents. Studying the details of p2p protocols and analyzing the
specific p2p overlay network instance become an alternative method
for this goal.
In this document, the content of P2P measurement is introduced
firstly, and then the existing research on P2P measurement is
classified into 3 areas: topology measurement, traffic measurement
and availability measurement. In each area, it gives the detailed
objects which are concluded from the current research work.
2. P2p measurement content overview
The main task of p2p network measurement is to measure the practical
networks, valuate the operation state of the p2p network and
establish the network behavior analytical model based on measurements.
The p2p network measurement can be divided into three types according
to different content:
1. p2p topology characteristics measurement: this measurement will
acquire the overlay topologies for different p2p applications,
analyze the graph property and dynamic property of the
corresponding topology.
2. p2p traffic characteristics measurement: this measurement will
acquire all kinds of statistical parameters of p2p traffic,
analyze the space characteristics and time characteristics.
3. p2p availability characteristics measurement: this measurement
will measure the availability for p2p node, resource and ect.
3. P2p measurement methods
According to the different measurement style, the p2p measurement
methods can be divided into active measurement method and passive
measurement method.
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3.1. Active measurement method
The active method is to use network crawler to actively join the p2p
network and then get the related properties of the network and peers.
Generally, the crawler joins the p2p system just like the ordinary
peer and then collects the correlative information as much as
possible which usually includes the IP address and port number of
peers and all the metadata which can be obtained by p2p protocol.
The active method is mainly used to measure the topology, delay,
content availability, peer's microscopic behavior such as
upload/download in p2p network.
The biggest shortcoming of this method is lack of generality and we
must set up sole crawler for each p2p network.
3.2. Passive measurement method
The passive method is to deploy some measurement points at different
location interspersed in the network and use the specific software
and hardware devices to passively monitor the p2p traffic. In order
to the universality of the measurement data, the measurement location
is generally at the core router in the backbone network or at the
edge entrance of one IPS network.
This method is used to measure the macroscopic properties of p2p
traffic such as traffic bandwidth of p2p traffic, the number of peers
and the peer connection lasting time.
The biggest shortcoming of this method is that it can't deeply
understand the p2p network behavior though it has good generality and
can measure many p2p applications.
4. The measurement indexes for p2p network
4.1. p2p topology characteristics measurement
The p2p system is an application overlay network Constructed over the
internet and its topology mainly describes the arrangement mode of
its peers and how the peers connect to each others. The neighbor
selection policy and peer's join/exit make the p2p application have
the natural dynamic property which causes great difficulty for large
scale p2p network topology measurement. However, the current p2p
topology characteristics measurement includes graph property
measurement and dynamic property measurement.
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4.1.1. Graph property measurement
The graph property measurement includes four index: the distribution
of peer connectivity, the distribution of the distance between any
pair of peers, the small world property and the topology elasticity.
The distribution of peer connectivity is to study the number of
connection of one peer, also called in-degree/out-degree.
The distribution of the distance between any pair of peers is to
study the shortest path from one peer to any other peer according to
hops. [Stutzbach2005] shows that 60 percent paths have 4 hops coming
from four measurements.
The small world property is to study the cluster degree of p2p
topology which usually is weighed by clustering coefficient.
[Stutzbach2005] showes that the Gnutella 0.6 network has this
property.
the topology elasticity is to study the connectivity changes after
deleting some peers.
4.1.2. Dynamic property measurement
For the peer randomly joins/exits the p2p network, the p2p network
topology dynamically changes at the all time. So the study for p2p
network dynamic property is at the starting stage and the current
measurement includes: the connectivity changes among the stable core
overlay, the distribution of peer session time, the distribution of
download time and the association with session time.
One focus study is to measure churn which is dynamic change caused by
peer joins/exits p2p network. The common indexes which describe the
churn include session time, lifetime, availability and etc.
4.2. p2p traffic characteristics measurement
The p2p traffic characteristics are usually acquired by passively
monitoring the network packets. Along with the development of the p2p
traffic concealment technology and the inhomogeneous distribution of
the peers, how to ensure the accuracy and representativeness of the
p2p traffic statistical data becomes the most important problem for
p2p traffic measurement. The p2p traffic characteristics measurement
includes the space characteristics and time characteristics
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4.2.1. space characteristics measurement
The space characteristics of p2p traffic include two sides: one is
the distribution on Regional difference from the macroscopic view,
the other is the heterogeneity between different peer.
4.2.2. time characteristics measurement
The time characteristics of p2p traffic also include two sides: one
is activity during time of day from the macroscopic view, the other
is self-similarity characteristics from the microscopic view.
4.3. p2p availability characteristics measurement
The p2p network availability describes the degree how the user
obtains the services. The p2p network availability is not only
related with the each peer's availability, but also with the
connectivity state of the whole network and peer's join/exit behavior.
The p2p availability measurement includes host availability
measurement and content availability measurement.
4.3.1. host availability measurement
The host availability in p2p network is expressed by the host active
time and the ratio of active host. The general method is to randomly
select a host set under test from the specific p2p network,
periodically send probe messages and count the number of responses.
4.3.2. content availability measurement
The content availability describes the difficult degree that the user
can obtain the target resource for p2p system, that is the difficult
degree of user querying and downloading resource. The related factors
which influence the content availability is more complicated than
those of the host availability, so we only indirectly reflect this
index through five indexes: the number of reply for a query, the
query response time, the content stability, the multiplicity of the
content, download finishing time.
According the above five indexes, [Christin2005] shows that the
network topology is closely related with the content availability,
the multiplicity of the content usually follows the power-law
distribution.
For protecting the digital right, some ICPs use the content pollution
technology in p2p network. The content pollution has important impact
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for the content availability and how to measure the pollution degree
is under studying.
5. Future work
The future work is to give some detailed measurement indexes for p2p
system. If possible, we will give the detailed indexes for some
typical and popular p2p system, such as p2p file system, p2p
streaming system.
6. Acknowledgements
No acknowledgements at this time.
7. Security Considerations
This draft does not introduce any new security issues.
8. IANA Considerations
This memo includes no request to IANA.
9. References
9.1. Normative References
9.2. Informative References
[Stutzbach2005] Stutzbach D, Rejaie R, Sen S. Characterizing
unstructured overlay topologies in modern P2P file-sharing
systems. In: Proc. of the 5th ACM SIGCOMM Conf. on Internet
Measurement. 2005.
[Christin2005] Christin N, Weigend AS, Chuang J. Content availability,
pollution and poisoning in peer-to-peer file sharing
networks. In: Proc. Of the 6th ACM Conf. on Electronic
Commerce (EC 2005). 2005.
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Authors' Addresses
Jin Peng
China Mobile
Beijing 100045, China
Phone: 86-13911281193
Email: pengjin@chinamobile.com
Lifeng Le
China Mobile
Beijing 100045, China
Phone: 86-13910019925
Email: lelifeng@chinamobile.com
Shihui Duan
China CATR
Beijing 100045, China
Phone: 86-10-62300068
Email: duanshihui@catr.cn
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