On Thu, 2007-10-11 at 12:22 +1000, Lawrence Stewart wrote:
> Hi Byung-Hee,
>
> Byung-Hee HWANG wrote:
> > On Wed, 2007-10-10 at 11:42 +1000, Lawrence Stewart wrote:
> >
> >> Hi All,
> >>
> >> Just 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
> >> information.
> >>
> >> The software and documentation is freely available under a BSD licence
> >> from:
> >>
> >> http://caia.swin.edu.au/urp/newtcp/tools.html
> >>
> >> We would be very happy to hear from anyone regarding bugs and
> >> suggestions as well.
> >>
> >
> > First of all, I would like to thank you for your good efforts. Its
> > almost feature seems like PF(4), however, it's useful to me, maybe.
> >
>
> Thanks!
>
> w.r.t. PF, as far as I'm aware, it does not allow the user to drop
> arbitrary packets identified by number within a TCP flow. Dummynet with
> its uniform packet loss pipe configuration is about the closest thing to
> DPD that I know of. The problem with Dummynet's uniform packet loss is
> that you have no control over which packets get dropped, which makes
> analysing TCP behaviour very difficult indeed. That said, I could simply
> be blissfully unaware that such functionality exists in PF.
>
> > Are you willing to support IPv6 for both SIFTR and DPD?
> >
> In the short term, our research does not entail the use of IPv6 and
> there is currently insufficient time available for implementing
> functionality that is not immediately useful to us.
>
> That said, it should be fairly straight-forward work to add IPv6
> support, and I'd be more than happy to give you all the pointers and
> tips required to carry out the modifications if you were so inclined.
I don't want that my comment can force your thinking for implementing.
IPv6 support, it was just my wish list for your software. So never mind.
And if I encounter strange problems, then I'll give you email;;
Thanks,
--
Byung-Hee HWANG <[EMAIL PROTECTED]>
"Michael, it's not true, please say it's not true."
-- Kay Adams, "Chapter 31", page 434
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