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Multiple sources in the same location
We now consider paths from pairs of hosts in the same location but on
entirely different networks to destinations in the UnivHosts set. We
consider two such pairs of traceroute sources: (a) a machine on the
Berkeley campus and another also in Berkeley but on @Home's cable
modem network, and (b) a machine at the University of Washington (UW)
campus in Seattle and another on the Microsoft Research network 10 km
away.
Figure 4:
CDF of distance ratio for paths from pairs of co-located sources to UnivHosts.
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Figure 4 shows the CDF of the distance ratio for
all 4 sources. For the two sources located in Berkeley, we find that
the one on the university campus has a significantly smaller distance
ratio, especially at the tail of the distribution. For instance, the 90th
percentile of the distance ratio for the UC Berkeley source is 1.41
while that for the cable modem source is 1.83. Since the destination
set is UnivHosts, the UC Berkeley source tends to have more direct
routes (via Internet2) than the cable modem client has (via @Home and
other commercial ISPs).
We observe a similar trend for the UW-Microsoft pair. The UW source has
more direct routes to other university hosts than does the Microsoft
source. For instance, the path from Microsoft to the University of
Chicago follows a highly circuitous route through BBNPlanet's
(Genuity) network. The geographic path traversed includes Los Angeles,
Carlton (TX), Indianapolis and Chicago (in that order). The linearized
distance of the path is 4976 km while the geographic distance between
Seattle and Chicago is only 2795 km. In contrast, the path from UW
(via Internet2) is far more direct: it passes through Denver, Kansas
City, Indianapolis, and finally Chicago, for a total linearized
distance of 3533 km.
These results indicate that the nature of network connectivity of the
source and the destination has a significant impact on how direct or
circuitous the network paths are.
Next: Effect of geographic location
Up: Effect of network location
Previous: Paths from a single
Lakshminarayanan Subramanian
2002-04-14