[BitTorrent] Re: Would it be possible to add to UDP and STUN?

weezul_fenderson weasel at havoc.gtf.org
Sun Sep 26 20:15:29 EDT 2004

> UDP transfers are tricky to implement properly.

Do you mean that the network might choose to drop your packet because
its "out of date" and the network assomes its something like voice?  This
sounds like an easy matter for error correction, although I believe that the
curren BitTorrent error correction may be insufficent.

Anyway, I believe that someone would need to research the rate of
packet lose..  possibly by writing the code, and experementing.
Obviously, clients without NATs would disable UDP to prevent waist
of bandwidth, but hosts behind NATs who had extra bandwidth could 
choose to use UDP.  I have absolutely no idea if this would help
torrents with large  numbers of users, but I have a hard time imagining
it not helping torrents with few users.

Maybe someone has done the research without writing the code, and
intelegently deemed  that "only small torrents which I don't care about"
would use this, but I suspect that no one has really seriously looked at
the problem.

> STUN doesn't make sense for TCP. 

Okay, that is good to know.

> Even using UDP transfers and some kind of hole-punching trick for 
> the firewalls of two nodes, they can't necessarily talk directly to
> each other.

I have yet to encounter a firewall which stops SIP communications
like SIP phones, iChat, and [maybe] AIM.  I know they exist, but they
are rare.. multiple layers of NAT on both ends is not a problem either.
STUN is not 100%, but it sure seems to be like 95%.. and SIP 
supporters are pushing hard for firewalls to permit it.

Or do you mean something diffrent?


P.S.  UDP and STUN are being discussed for P2P by people ouside the BitTorrent 
community.. maybe its more a feature of "swarm size" which would make this a priority.

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