On Wed, Nov 10, 2004 at 04:21:16PM +0700, Philippe wrote:
> Reply-To: For users of Fedora Core releases <fedora-list@xxxxxxxxxx>
> On Wed, 2004-11-10 at 14:19, Nifty Hat Mitch wrote:
> > On Tue, Nov 09, 2004 at 06:00:33PM +0700, Philippe wrote:
> >
> > >
> > > First time using bittorent .. on a dialup. I will not tell you how long
> > > I need to download FC3 :-) ... but this is not the point.
> >
> > Philippe,
> >
> > I am a fan of bittorrent but on a dialup you are not likely to
> > contribute to to the torrent in ways that you might expect.
....
> > $ netstat -an | grep 6[0-9][0-9][0-9] | grep ^tcp
or lsof for the torren process id is good too.
.....
> That was exactly the kind of things I was thinking. Do I harm the other
> users, taking parts from my download.
Yes and No. With a saturated dialup lots of packets get
to stand in line at both ends. This increases latency which
is already a problem for dialup.
I did some packet snooping on my early BT sessions a year or so ago.
The number of connections and the number of apparently lost packets
(resent) was much larger than I expected.
I did some cautious ping and traceroute inspections and it was
clear that BT works in ways that I did not expect.
Run btdownloadcurses.py with no flags and look at the option
list.... it has lots of knobs to dial. Read the notes
and inspect packet traffic to see what I mean.
If the download and upload statistics match things are good enough.
If you wish to run BT for days after you get all the bits do
try and tune things for the long run.
The key is that BT slices an object into lots of parts and maps those
parts to a 'bit map'. A central service presents those that ask with
the location of hosts with chunks to share. A set of connections are
made and chunks pass too and fro. When the bitmap is full the
file has been downloaded and a MD5 check sum verifies things.
The key to being a good guy is to accept only as many connections as
you can deliver bits to without timouts and without silly slow bit
rates per connection.
Currently there is no 'profile' hook that I know of that would make it
easy for the novice tune things. It might be nice to have hooks
"--link_type" and "--link_percent" that would let system admin folks do
something like:
--link_type DIAL --link_percent=50
--link_type ADSL --link_percent=70
--link_type SDSL --link_percent=50
--link_type T1 --link_percent=50
I see little reason for a dialup (or ADSL/cable modem)to accept 35-50
connections in both directions which is what it does now as best I
can tell.
None of this is intended to be critical. The great value of BT is
that it can be tuned in ways that folks with great and small link
bandwidth can contribute in positive ways.
--
T o m M i t c h e l l
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