[e2e] Software for FreeBSD TCP R&D: SIFTR v1.1.4 and DPD v1.0 released

Lawrence Stewart lstewart at room52.net
Tue Oct 9 18:58:01 PDT 2007

Hi All,

Further to Grenville's recent email regarding SIFTR, we just wanted to
give you a quick heads up regarding the availability of a new SIFTR
(Statistical Information for TCP Research) version and the debut release
of DPD (Deterministic Packet Discard).

SIFTR v1.1.4 addresses a couple of issues, one of which is applicable to
users of SIFTR in FreeBSD 7-CURRENT. Read the changelog and readme for
more information.

DPD is a new FreeBSD kernel module we developed to further aid us in our
ongoing TCP research. It allows for the deterministic dropping of TCP
packets from within the FreeBSD kernel via a simple sysctl interface.
This is particularly useful for anyone that is interested in observing
TCP reacting to packet loss events (e.g. congestion control
researchers). Being able to drop the same packet(s) across multiple
tests allows for simpler comparisons of TCP behaviour. We've found it
particularly useful in evaluating and observing the behaviour of
different congestion control mechanisms, and hope it may be of use to
others out there. Please refer to the DPD readme for more in-depth

The software and documentation is freely available under a BSD licence from:


We would be very happy to hear from anyone regarding bugs and
suggestions as well.



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