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layout slug status sitemap title description categories tags
post understanding-bittorrent draft false Understanding BitTorrent From the network perspective
p2p
distributed system

In this blog post, we will only review the core of BitTorrent. We are not interested in its extensions, its optimizations, how it manages spam, etc.

Compared to the specifications, we will focus our analysis on the importance of parameters and the emerging behaviours that arise when many BitTorrent clients communicate together. Moreover, as this (hopefully series of) article will be written in a goal to evaluate Peertube planned implementation of "webstream" (live-streaming over webtorrent), we will use the webtorrent implementation as reference for everything outside specifications.

We will also try to connect BitTorrent design to some academic papers to put things in perspective.

A problem well stated is a problem half solved

Discover content

Discover peers

Discover peers' content

Induce a desirable emerging behavior

The .torrent file

Describes the content of the file to download. Multiplexing.

The role of the tracker

Discovering peers. What property it must enforce. Random sample of the network You will have some neighbors.

Discovering the chunks known by your neighbors

introduce some Xerox Taxonomy {% cite DBLP:journals/sigops/DemersGHILSSST88 %}. "bitfield" puis "have" -> le push sur l'anti entropy If it's done symmetrically, we are in a push+pull model.

Downloading the data

The importance of Local Rarest First {% cite DBLP:conf/infocom/BharambeHP06 %}

Conclusion

BitTorrent is efficient as it multiplexes chunks.

References

{% bibliography --cited %}