[bittorrent] Open letter to the BBC

Brian Dessent brian at dessent.net
Sun Jun 19 18:05:05 EDT 2005


larytet.8708132 at bloglines.com wrote:

> regarding 50%
> overhead. i witnessed the traffic in my firewall on dayly basis when downloading
> from big swarms with small number of seeds. overall traffic reported by my
> firewall in some cases was more than double of what actual data download i
> got. IP sniffer in that time reported up to 10 "I have " packets for evey
> "useful" data packet.

That only happens if you have your client configured to allow unlimited
(or a very large number of) connections.  In a large swarm it is very
prudent to limit the max number of connections to something sane, such
as 75 or 100.  Otherwise the amount of chatter just gets too high,
unless the host is on a fast connection and is uploading great amounts. 
Last I looked the mainline client was limiting it to something slightly
less than 64.  I don't know what values typical clients ship with these
days, but the above described scenario is typical of a poor
implementation and has nothing to do with the protocol.  If there aren't
a gazillion connections and yet still 50% of your bandwidth is 'haves',
then that means that something is seriously wrong, since those peers
must by definition be downloading orders of magnitude faster than you.

I'd also like to say that, while I'm sure that rodi is great and all,
this is a BitTorrent list and discussions of other protocols are
off-topic.  Please don't hijack every single thread to plug your shit.

Brian



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