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1. What is BT?
1. Introduction to BT:
1.1. BT is one of the most popular downloading methods at present. Its full name is "BitTorrent" for short "BT", and its full name in Chinese is "Bit Stream". But many friends jokingly call it "abnormal downloading". What is the reason? As far as downloading methods such as HTTP, FTP, and PUB are concerned, the file is generally first put on the server, and then the server transmits it to each user's machine. Its working principle is shown in Figure 1. Therefore, if there are too many users downloading at the same time, it will inevitably affect the download speed of all users. If some users use multi-threaded downloads, the impact on bandwidth will be even more serious. Therefore, almost all download servers have restrictions on the number of users and the maximum download speed. Obviously, due to the above reasons, even if you are using a broadband network, it is usually difficult to achieve the maximum download speed promised by the operator. Although there are reasons for the network, it is not unrelated to the limitation of the server. Because of this, after the BT download method appeared, it quickly became the favorite of download fans.
1.2. The BT server implements file sharing through a pyramid scheme, and its working principle. For example, if the BT server divides a file into N parts, and four users A, B, C, and D download at the same time, then BT will not completely download all parts of the file from the server, but selectively download the downloaded parts from other users' machines according to the actual situation. For example, A has downloaded part 1, and B has downloaded part 2, then C will download part 1 from A's machine, and download part 2 from B's machine. Of course, three users A, B, and D are also downloading the corresponding part from C's machine at the same time, which greatly reduces the load on the BT server and speeds up C's download speed.
2. Small knowledge:
2.1. Do you know what is the difference between BT download and regular download? The difference from regular download is that when you download BT, the address you start linking to is a file ending in .torrent. In fact, as long as you download this file, you can also perform BT download work by running this file on this machine. The BT download links on the Internet are all provided by users themselves, which makes the download data very wide and is not restricted by conventional management personnel.
2.2. The soul of BT download: seeds. No matter what kind of BT client program, the default setting does not limit the download speed and upload speed. This is because the BT software will give priority to users with faster upload speeds. That is to say, the faster the upload speed, the faster the download speed. Therefore, if you are using broadband, you don’t need to limit the upload speed when downloading.
2.3. When the download is over, if you do not close the BT client program (for example, while running BT to provide upload services, while browsing the web, editing documents, etc.), then you will become a messenger to pass the torch, that is, "seed". In other words, if a file is divided into 10 parts, but there is only one person who owns part 9, that is, only one seed, if this user disconnects or shuts down for some reason, then other users can only download 90%, which is the most distressing when performing BitTorrent downloads.