Understanding BGP
Misconfiguration. Ratul Mahajan,
David Wetherall and Tom Anderson( It is well-known that simple, accidental BGP configuration
errors can disrupt Internet connectivity. Yet little is known about the
frequency of misconfiguration or its causes, except for the few spectacular
incidents of widespread outages. In this paper, we present the first quantitative
study of BGP misconfiguration. Over a three week period, we analyzed routing table
advertisements from 23 vantage points across the Internet backbone to detect
incidents of misconfiguration. For each incident we polled the ISP operators
involved to verify whether it was a misconfiguration, and to learn the cause
of the incident. We also actively
probed the Internet to determine the impact of misconfiguration on
connectivity. Surprisingly, we find that configuration errors are
pervasive, with 200-1200 prefixes (0.2-1.0\% of the BGP table size) suffering
from misconfiguration each day. Close to 3 in 4 of all new prefix advertisements
were results of misconfiguration. Fortunately, the connectivity seen by end
users is surprisingly robust to misconfigurations. While misconfigurations
can substantially increase the update load on routers, only one in twenty
five affects connectivity. While the
causes of misconfiguration are diverse, we argue that most could be prevented
through better router design. Papers are provided as
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paper is available in Adobe PDF format. |