[BitTorrent] Some complement about Tracker-tracker communication

Harold Feit - Depthstrike.com Administrator dwknight at depthstrike.com
Mon Feb 21 10:04:07 EST 2005

Hash: SHA1

On windows, the number of connections you need to use to reach the
limit is around the number of connections required for 2000-5000
peers with a best-seen of a little under 10,000 peers (I know it's
not many, but it seems that the windows TCP/IP stack doesn't like
having dozens-thousands of half-closed connections lying around).

On linux, the number of connections you need to use to reach the
limit is around the number of connections required for 1,000,000+
peers, although it may be less because of other limitations such as
routers (if I remember right, we have yet to see a single tracker
actually reach these sort of limits, most trackers are hitting
interest limits in the 300k-400k range).

UDP _MAY_ solv some of the problems involved here, but there doesn't
seem to be enough acceptence by the development community for it to
be useful as a solution to this problem.

When I hit the 10,000 peer limit of Windows, the bandwidth used
(pre-compact implementation on my tracker) was less than 10kbyte/sec.

- -----Original Message-----
From: Justin Cormack [mailto:justin at street-vision.com] 
Sent: Monday, February 21, 2005 5:34 AM
To: BitTorrent at yahoogroups.com
Subject: Re: [BitTorrent] Some complement about Tracker-tracker

> Tracker-Tracker communication already has some implementation in
> real-world environments.
> BNBT based trackers running on versions 7.3, 7.7, and 8.0 have the
> capability (with the consent of the administrators of both
> trackers) to share ALL peer data.
> I personally operate a 5-way (not including the dedicated hub)
> linked tracker network. There are indeed several steps to take at
> the start to insure proper peer data sharing, but most have been
> documented at http://cbtt.depthstrike.com/trackerlinks.
> Additionally, deployment guidelines have been documented there as
> well.

Just a few questions about these:

I see the main point is not listed as being bandwidth (despite what
people say about the huge importance of compact=1 suggesting that
are bandwidth limited) or even reliability (the solution has a single
of failure tracker hub apparently too, rather than peer to peer
solutions, though it will add some extra reliability), but number of

This is a bit surprising to me as the limiting factor, how many
are we talking about? And doesnt UDP tracker solve this by being
connectionless? Or are there other problems with udp, or is it just
widely used?


> I have been working on a php implementation of automated editing of
> tracker information within .torrent files and returning them to
> clients (in an effort to simplify my own tracker network's use).
> - -----Original Message-----
> From: guanying_wang [mailto:guanying_wang at yahoo.com.cn] 
> Sent: Saturday, February 19, 2005 7:21 AM
> To: BitTorrent at yahoogroups.com
> Subject: [BitTorrent] Some complement about Tracker-tracker
> communication
> The torrent file contains tracker address and file hash, which are
> the
> only useful infomation torrent file contains. Trackers can identify
> different torrent file by checking file hash, and Merkle Tree hash
> is short enough for quick identification. If we can turn to wide
> deployment of Merkle Tree as soon as possible, I think
> tracker-tracker
> communication will be very easy to implement.

It doesnt make much difference whether you use Merkle tree or info
they are the same size.
> Scalability is good, because capacity can effectively be improved
> by simply adding additional trackers.
> Thank you.
> Guanying
> PS: I haven't seen my first post till now. God knows when I can,
> maybe
> tomorrow... How do you guys use this list? I think the web
> interface is not good enough. RSS, either. Thank you.

There are moderation delays sometimes, on all interfaces. I use the
version, havent seen the first post either...

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