[H-GEN] Bittorrent query

[David Jericho]

Geoff Shang wrote:

> To bittorrent specifically.  I understand that if you don't provide the
> ability for people to upload from you, your download rate suffers
> dramatically. 

Not entirely true.

It's the client that enforces this rule, and it's easy enough to get
around whatever client you're using. My own experiences with well
connected hosts has verified this. Speeds of 20 - 30 MByte/s down, with
1 Kbyte/s up upon joining a multiple gigabyte torrent, enforced by using
the --max_upload_rate command line option when using the official python
bittorrent client.

It's also possible to make Azuerus limit your upload rate without
impacting your maximum download rate.

Adjusting these parameters is particularlly important on assymmetric
links, where one direction has more avaiable capacity than the other.

As a rule of thumb, you need between 20 - 30% of the avaiable bandwidth
in the backchannel direction to max available incoming bandwidth. That
is, for every 10 kbyte/s down, you need to dedicate approximately 2 to 3
kbyte/s up. The figures aren't exact, and can vary hugely from protocol
to protocol, even more when you factor in things such as latency, jitter
and MTU size.

On your DSL link, assuming you have 512/128 you pretty much need to
dedicate almost all your backchannel to ensuring you flood your inbound
side.

-- 
David Jericho
Systems Administrator, AARNet
Phone:     +61 7 3864 8379
Mobile:    +61 4 2302 7185