P2P Flashcards
1
Q
How does BitTorrent work?
A
divides files into 256kb chunks
2
Q
define tracker
A
tracks peers participating in torrent
3
Q
define torrent
A
groups of peers exchanging chunks of a file
4
Q
define churn
A
the idea that peers come and go
5
Q
How does requesting chunks work in BitTorrent?
A
user downloading file request chunks from all other peers in torrent, acquires rarest chunks first
6
Q
How does sending chunks work in BitTorrent?
A
Tit for tat system:
user sends chunks to those four peers currently sending them chunks at highest rate
• other peers are choked by user (do not receive chunks from them)
• re-evaluate top 4 every 10 secs
every 30 secs: randomly select another peer, starts sending chunks
• “optimistically unchoke” this peer
• newly chosen peer may join top 4
