How do P3 and P5 handle this? P4 will make P8 it's first successor and will ask P8 for it's first successor and then make that Pk into it's second successor. P3's first successor is P4 and second successor is P5. Simply needs to request the different chunks and combine them back together P4's first successor is P5, and second successor is P8. How can he do that? (a) Assuming there remains a large enough number of peers in the swarm is it possible for Bob to receive data through optimistic unchoking by other peers Is Bob's claim possible? Why or why notī) Bob further claims that he can further make his "free-riding" more efficient by using a collection of multiple computers (with distinct IP addresses) in the computer lab in his department. Suppose Bob joins a BitTorrent torrent, but he does not want to upload any data to any other peers (so called free-riding).Ī) Bob claims that he can receive a complete copy of the file that is shared by the swarm. Given N active peers, there will be N nodes and N(N-1)/2 active edges. Therefore, the value M is not important in this calculation. How many nodes and edges are there in theĬorresponding overlay network? Overlay networks are abstractions of the actual physical network occurring below between peers. Additionally, suppose that the TCP connections pass through a total of M routers. P2P = 7680 Consider an overlay network with N active peers, with each pair of peers having an active TCP connection. For N = 10 and u = 300 Kbps find the minimum distribution time for both client-server distribution and P2P distribution. The server has an upload rate of us = 30 Mbps, and each peer has a download rate of di = 2 Mbps and an (c) If all five users open five parallel instances of non-persistent HTTP, then would Bob's parallel connections still be beneficial? Why or why not?Ĭonsider distributing a file of F = 15 Gbits to N peers. Bob uses parallel instances of non-persistent HTTP, and the other four users use non-persistent HTTP with-out parallel downloads. (b) Now suppose that the link is shared by Bob with four other users. (a) Do you expect significant gains over the non-persistent case? Justify and explain your answer. Would parallel downloads via parallel instances of non-persistent HTTP make sense in this case? Now consider persistent HTTP. Now consider the HTTP protocol, and suppose that each downloaded object is 100 Kbits long, and that the initial downloaded object contains 10 referenced objects from the same sender. Assume that N parallel connections each get 1/N of the link bandwidth. Suppose that packets containing data are 100,000 bits long, and packets containing only control (e.g., ACK or hand-shaking) are 200 bits long. Consider a short, 10-meter link, over which a sender can transmit at a rate of 150 bits/sec in both directions.
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