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<b>URL:</b>
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<a href="http://www.sds.lcs.mit.edu/papers/clustering-imw2002.html">http://www.sds.lcs.mit.edu/papers/clustering-imw2002.html</a><br/>
<a href="http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.20.3060">http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.20.3060</a>
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<b>Entry Date:</b>
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2003-01-22


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<b>Abstract:</b>
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This paper describes a method of inferring logical relationships
between network prefixes within an Autonomous System (AS) using only
passive monitoring of BGP messages. By clustering these prefixes based
upon similarities between their update times, we create a hierarchy
linking the prefixes within the larger AS. We can frequently identify
groups of prefixes routed to the same ISP Point of Presence (PoP),
despite the lack of identifying information in the BGP
messages. Similarly, we observe disparate prefixes under common
organizational control, or with long shared network paths. In addition
to discovering interesting network characteristics, our passive method
facilitates topology discovery by potentially reducing the number of
active probes required in traditional traceroute-based Internet
mapping mechanisms.


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<b>Datasets:</b>
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BGP announcements were collected from a router which peered with MIT's
border router. Data was collected from June 28, 2001. MIT obtains upstream
connectivity from
Genuity (AS 1) and the Northeast Exchange (via AS 10578). On April 18, 2002,
a private link between MIT and AT&amp;T Broadband (AS 7015) was established.
Clustering (see Results below) was performed on prefixes announced by UUNET
(AS 701) and AT&amp;T (AS 7018).
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A static routing table snapshot was taken at MIT on April 11, 2000. This table
was used to perform further selection of prefixes from the above set.
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<b>Results:</b>
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Presents a fully passive, BGP-based topology inference method.
Prefixes are grouped based upon how frequently BGP updates for each pair of
prefixes are observed within the same time window. A standard clustering
algorithm is then applied to join these prefixes into successively larger
groups.
The authors claim that their temporal clustering produces higher-fidelity
topologies than other passive, BGP-based approaches. An example of a
drawback of other approaches is that many large ISPs announce a large number
of prefixes under the same AS path.


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<b>References:</b>
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<ul>
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"Skitter," http://www.caida.org/tools/measurement/skitter/, 2002.
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Ramesh Govindan and Hongsuda Tangmunarunkit,
"Heuristics for Internet Map Discovery,"
in IEEE INFOCOM 2000. IEEE, Mar. 2000, pp. 1371-1380.
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Balachander Krishnamurthy and Jia Wang,
"On network-aware clustering of web clients,"
in Proc. ACM SIGCOMM, 2000.
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<li>
Neil Spring, Ratul Mahajan, and David Wetherall,
"Measuring ISP Topologies with Rocketfuel,"
in Proc. ACM SIGCOMM, Aug. 2002.
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