problem 1) prepare down two reasons a company might prefer to pay Akamai to host their webpage instead of putting it onto a peer-to-peer network (like Napster) for free.
problem 2) Peer-to-peer file sharing systems require a way to permit peers to determine which other peers have the content they want. Compare and contrast the approaches taken by Napster (a centralized database), Gnutella (request ooding), and BitTorrent (distributed hash tables).
problem 3) David is torrenting a movie. Suppose all other BitTorrent users in the network are using a standard client and:
i) Have an active set size of four
ii) Equally split upload bandwidth among peers in their active sets
iii) Have all of the chunks of the movie David is downloading
The other peers in David's neighbourhood are listed below, along with the total upload capacity of each as well as the rate at which it is receiving data from the slowest peer in its active set.
Peer # Total Upload Capacity Download rate from slowest active peer
1 100 Kbps 100 Kbps
2 2000 Kbps 300 Kbps
3 800 Kbps 200 Kbps
4 800 Kbps 400 Kbps
5 1200 Kbps 100 Kbps
6 400 Kbps 225 Kbps
Assume that David has an infinite download capacity and upload capacity of 1 Mbps. Ignore optimistic unchoking for all peers in network, including David (that is, in the problems below, don’t take into account the upload cost or the download benefit of optimistic unchoking).
Suppose that if David offers a peer the same upload rate as another user in that peer's active set he will sometimes win and replace that user in the peer's active set.
(a) If David is using standard BitTorrent client with same properties as the rest of the peers in the network, determine the maximum download rate he can achieve?
(b) If David switches to BitTyrant, determine the maximum download rate he can achieve?