NSDI '08 – Abstract
Pp. 247–262 of the Proceedings
Studying Black Holes in the Internet with Hubble
Ethan Katz-Bassett, Harsha V. Madhyastha, John P. John, and Arvind Krishnamurthy, University of Washington; David Wetherall, University of Washington and Intel Research; Thomas Anderson, University of Washington
We present Hubble, a system that operates continuously to find Internet
reachability problems in which routes exist to a destination but packets are
unable to reach the destination.
Hubble monitors at a 15 minute granularity the data-path to prefixes that cover 89% of the
Internet's edge address space. Key enabling
techniques include a hybrid passive/active monitoring approach and the synthesis of multiple information sources that include historical data.
With these techniques, we estimate that Hubble discovers 85% of the
reachability problems that would be found with a pervasive probing approach,
while issuing only 5.5% as many probes. We also present the results of a
three week study conducted with Hubble. We find that the extent of
reachability problems, both in number and duration, is much greater than
we expected, with problems persisting for hours and even days, and many of
the problems do not correlate with BGP updates. In many cases, a
multi-homed AS is reachable through one provider, but probes through
another terminate; using spoofed packets, we isolated the direction of
failure in 84% of cases we analyzed and found all problems to be
exclusively on the forward path from the provider to the destination.
A snapshot of the problems Hubble is currently monitoring can be found at
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