Summary: Quantifying the Causes of Path Inflation
Neil Spring Ratul Mahajan Thomas Anderson
{nspring,ratul,tom}@cs.washington.edu
Computer Science and Engineering
University of Washington
Seattle, WA 98195­2350
ABSTRACT
Researchers have shown that the Internet exhibits path inflation --
end­to­end paths can be significantly longer than necessary. We
present a trace­driven study of 65 ISPs that characterizes the root
causes of path inflation, namely topology and routing policy choices
within an ISP, between pairs of ISPs, and across the global Inter­
net. To do so, we develop and validate novel techniques to in­
fer intra­domain and peering policies from end­to­end measure­
ments. We provide the first measured characterization of ISP peer­
ing policies. In addition to ``early­exit,'' we observe a significant
degree of helpful non­early­exit, load­balancing, and other poli­
cies in use between peers. We find that traffic engineering (the ex­
plicit addition of policy constraints on top of topology constraints)
is widespread in both intra­ and inter­domain routing. However,

Source: Anderson, Richard - Department of Computer Science and Engineering, University of Washington at Seattle
Spring, Neil - Department of Computer Science, University of Maryland at College Park

Collections: Computer Technologies and Information Sciences