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On the Geographic Location of Internet Resources

On the Geographic Location of Internet Resources. CSCI 780, Fall 2005. Motivation. Physical structure of the Internet Geometry of the Internet infrastructure Geographic locations of Internet routers, links, and ASes. Question is. Approach is. Two sets of questions. Where are the routers?

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On the Geographic Location of Internet Resources

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  1. On the Geographic Location of Internet Resources CSCI 780, Fall 2005

  2. Motivation • Physical structure of the Internet • Geometry of the Internet infrastructure • Geographic locations of Internet routers, links, and ASes

  3. Question is

  4. Approach is

  5. Two sets of questions • Where are the routers? • What is the relationship between population and density of routers?

  6. Where are the routers

  7. Population vs Routers • Router density per person varies widely across economic regions • Raito of on-line people to routers shows much less variability • In economic homogeneous region • The number of routers per person is higher in areas of high population density

  8. Superlinear relationship

  9. Link density vs distance • Large majority of link formation is influenced by geographical distance • Link (connectivity) patterns show a strong relationship to distance • 75%-95% of links are distance-sensitive • A small fraction of links is insensitive to distance • Play an important structural role

  10. Distance preference function

  11. Two classes of links

  12. Autonomous Routing Domains A collection of physical networks glued together using IP, that have a unified administrative routing policy. • Campus networks • Corporate networks • ISP Internal networks • …

  13. … the administration of an AS appears to other ASes to have a single coherent interior routing plan and presents a consistent picture of what networks are reachable through it. RFC 1930: Guidelines for creation, selection, and registration of an Autonomous System Autonomous Systems (ASes) • AS is a set of routers under a single technical administration An autonomous system is an autonomous routing domain that has been assigned an Autonomous System Number (ASN).

  14. AS Numbers (ASNs) Over 11,000 in use. ASNs are 16 bit values. • Genuity: 1 • MIT: 3 • Harvard: 11 • UC San Diego: 7377 • AT&T: 7018, 6341, 5074, … • UUNET: 701, 702, 284, 12199, … • Sprint: 1239, 1240, 6211, 6242, … • … 64512 through 65535 are “private” ASNs represent units of routing policy

  15. Two geographic properties of ASes • Number of distinct locations spanned by an AS • Size of AS • Geographical dispersion of an AS’s components (routers) • How an AS place its routers

  16. Size of AS • Number of degree in the AS-graph (done before, SIGCOMM’99) • Number of routers within one AS (done before, CCR’01) • Number of distinct locations spanned by one AS Observed distribution is highly variable, with long tail spanning many orders of magnitude (Power-law)

  17. How does AS place its routers? • Majority of ASes (around 80%) have either one or two locations (zero area) • Among the remaining ASes, there is considerable variability in geographical dispersion

  18. Geographic dispersion • Small to medium Ases show wide variability in their geographical dispersal • Largest Ases (exceeding certain threshold) are maximally dispersed geographically

  19. Domain and Link length • Inter-domain link vs intra-domain link • Inter-domain links tend to be twice as long as intra-domain links • Majority of links (83% or more) are intra-domain. • Average length of inter-domain links approaches or exceeds the limit of distance sensitivity

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