More on bittorrent

[Kam Leo]

On 2/26/07, Aaron Konstam <akonstam at sbcglobal.net> wrote:
> >>
> >>Aaron Konstam wrote:
> >> I wanted to download the latest FC6 respin CDs. I went to the web
> >> location and found the correct bittorrent and clicked to download it.
> >> The bittorrent GUI opened and the download started. Now I was
> connected
> >> to a system with an Internet speed of 45 Mb/s but the GUI said the
> >> download would take 15 hours. Well the respin has 5 CDs. I have a
> >> downloaded a single 600+ Meg CD in less than an hour (actually I
> think
> >> it was much less). So I can't understand why the bittorrent download
> >> should take 15 hours.
> >>
> >> I have done this before but it has been a long time ago. I must be
> doing
> >> something wrong but what? Any ideas?
> >
> >A couple of things to check - do you have a download speed limit
> >set, so that it does not use the full bandwidth when downloading? Do
> >you have your firewall properly configured so that you can seed as
> >well as download? If not, this can limit your download speed. How
> >many seeds are there, compared to the number of clients, and how
> >many are you connected to?
> My download speed was set too high. I have no firewall set on my machine
> but the university does however they tell me that they do not restrict
> bittorrents. I don't know how to check the number of seeds and /or
> number of clients.
>
> So there are clearly holes in my knowledge. Can someone help fill in the
> gaps.
> >
> >One other thing to keep in mind is that the time estimate when you
> >first start downloading is usually high, and drops as you connect to
> >more feeds. It also tends to change during the download. Depending
> >on how the client calculates the time remaining, it may get less
> >sensitive to rate changes as the download progresses - more data to
> >average, so temporary fluctuations in download speed do not affect
> >it as much.
> The above is true but I waited 2 hours and not even 1 CD was downloaded.
>

Bittorrent works when there are a large number of seeders and peers.
The problem with the Fedora respin is that after the initial
availability announcement the number of seeders and peers drops to a
very low number, less than 5 when I tried it. If each shares the
minimum required upload speed, 4K bits/second, the total bandwidth is
only 20K bits/second. Factor the low number of participants and the
problem of finding peers with the fragments missing from your download
and you get the current situation. Also I find that the tracker used
by Fedora respin does not work well with my setup which is behind a
firewall.