Measurement-in-the-middle: Inferring end-end path properties through passive measurements
Gianluca Iannaccone
In this talk, we consider the problem of inferring end-end path
properties and the behavior of TCP senders observing packets
crossing an IP backbone. We describe a measurement and analysis
methodology that we call "measurement-in-the-middle," that can be
used to characterize performance measures such as packet reordering,
loss, and delay from measurements taken at a single point in the
middle of the end-end path.
We propose a classification methodology for out-of-sequence packets
and a set of methods to infer and keep track of the sender's
congestion window and the connection round trip time. Given the
location of the measurement points within a large Internet Service
Provider, we are able to analyze more than 10 million connections,
with senders located in more than 45% of the autonomous
systems in today's Internet. Our measurements show a relatively
consistent amount of out-of-sequence packets of less than 5%.
We find that few packets experience pathological problems such as
in-network duplication or in-network reordering. Moreover, the
TCP sender throughput is frequently limited by a lack of data to
send, and the congestion control flavor often has minimal impact
on throughput.
This is joint work with Sharad Jaiswal, Jim Kurose and Don Towsley
(Univ. Massachusetts) and Christophe Diot (Intel).
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