Effect of upload speed on download speed?

[nicholasjohn]

Hello,

I'm a university researcher writing a book about sharing, in its broadest sense.

I'm writing a chapter on file sharing and I'm very interested in the ways that the norms of how people should share are technologically embedded in protocols and software.

I very much want to understand the BitTorrent protocol better, especially what difference to your download speed is made by your upload speed, and I thought there might be people here who would be able to help me with that, or direct me to someone/somewhere with knowledge. In a swarm, for instance, is download priority given to faster uploaders? To peers with a better ratio? In other words, how is the free rider problem dealt with and how are people encouraged to upload?

Thanks,

Nicholas

[ciaobaby]

https://wiki.theory.org/BitTorrentSpecification

http://user.utorrent.com/help/guides

[nicholasjohn]

Thanks.

I've looked at those. I'm kind of hoping for stuff that is a bit easier for a layman to understand.

What I do understand, though, is that if you don't allow any uploading to take place, your download will be much slower. But you still will be able to download, right?

Is there something in the protocol that tells users to prioritise peers with a high upload rate?

[ciaobaby]

What I do understand, though, is that if you don't allow any uploading to take place, your download will be much slower. But you still will be able to download, right?

Possibly.

Is there something in the protocol that tells users to prioritise peers with a high upload rate?

Not directly, but that IS what the "tit for tat" algorithm does.

http://en.wikipedia.org/wiki/Tit_for_tat#Peer-to-peer_file_sharing

A Microsoft research paper (PDF) on BitTorrent performance.

http://research.microsoft.com/en-us/um/people/cormac/papers/sigmetrics05.pdf

[nicholasjohn]

Those are very useful resources. Thanks a lot.