1. 12:59 5th Feb 2012

    Notes: 2

    Anonymous asked: aww saturday wasn't that productive for you :( do you get in any social interaction btw!? i'm sure you do, you probably just don't blog about it :) also how DOES bittorrent work exactly? Thanks :) and you seem really dedicated, good luck with everyting!

    It’s very hard to be productive on weekends!! As for social interaction on weekends, I like staying at home so the interaction occurs online. (I do have friends, I swear!)

    As for how BT was explained in class, each user connects to a tracker to get a list of other users participating in the torrent. Users establish a connection to a number of other users (for example, let’s say 10 users) and start downloading parts of files from them.

    After a certain amount of time, the user looks at the 10 users it’s connected to, and how much data they’ve received from them in that amount of time. The user will then “choke” (close) the connection with the user who has uploaded the least, and “optimistically unchoke” (connect to) a random user participating in the torrent, in hopes that they’ll upload more data than the previous user. This also allows the file to be distributed to more users, because otherwise the top 10 uploaders will just be transferring the files between each other, and everyone else just gets really slow rates.

    This encourages each user to upload data at a high rate, because it increases the chances to find users that will send you the files at a high rate and will keep you in their list of top peers.

    There’s also other stuff like sharing the rarest file fragment to make sure more users get it, and things like private trackers who kick you from the torrent if your ratio isn’t high enough and other things like that.

     
    1. halcy said: The best part of the BT protocol has got to be the optimistic unchoke. I mean, you’d think there was a better strategy than “pick someone at random”… turns out, not really, optimistic unchoke is seriously pretty darn good.
    2. walfas posted this