BitTorrent

BT is a kind of Internet emerging P2P transmission protocols, full name is "BitTorrent," prime creator is Bram Cohen, are independent development into a vast developers group of open mode transfer protocol.

Use skill

BT founder for Brahms Cohen

BT has been many individuals and enterprises to posted on the Internet various resources, its advantage is not to need resources publishers have high-performance server can quickly effectively release resources good-health to other BT client software users, and most of the BT software are free of charge.

Professional evaluation

The whole BT release system including, including the release of information resource files, as BT customer software server, the intermediary phrases of nationwide BT software users (often called peer). Publishers simply use BT software for their release resources to make the documents, will provide the people download, and ensure their BT software normal work, they can easily finish release. Downloaders as long as the files with BT software open, the software will be based on data provided by the file in the block and check information and phrases server address etc and other running BT software computer contact, and complete transmission.

Because BT between the software several transmission is bidirectional, this to reduce the dependence of publishers bandwidth. And another kind of common P2P software, different, BT agreement did not adopt to the user uploads and downloads ratio and landing sequence and whether can receive inbound requests to synthetical arrangement for uploading. BT software at most of the time would constantly compare other BT client to avail itself of the speed of data transmission, and priority to self to transmit data faster client (publishers and download completed (often called seed or seed) would be different, because they do not download data, sorting by each other's download speed).

Although Bram Cohen says BT agreement effectively use the Internet is a Peano effective bandwidth, a lot of telecom service providers complain BT transmission occupied too much bandwidth, has greatly affected the the others on the network applications (such as to network performance requirements of high online voice, online vod), each big telecom service providers from global statistics are shown, BT transmission has accounted for online all data transmission over 70% of the telecom service providers, many unilateral action has been taken to BT transmission restriction from gentler data transmission to adjust to the priority degrees detected BT transmission, telecom service providers directly shielding says this is to protect the rights and interests of other users that telecom service providers mostly BT users of action violates them and service of service agreement signed, believe that since bandwidth is used not quite, telecom service providers have the obligation to equipment of improved.

In order to cope with the telecom service providers to BT transmission restriction, mainstream BT software has made a lot of improvement, telecommunication services of the restrictions, bypassing the widespread use of methods include, through to the files based on client identity authentication and the data diffie-hellman encryption to prevent the telecom service provider detects, use DHT distributed network as phrases server complement, random selection of transmission port.

Because the release and spread on BT advantages, there are a lot of tort content is released, the defendant by BT suspected of infringing the release and encourage download content, the world's largest BT release and resource site entire NOVA has forced the closure of index, including MPAA and RIAA, copyright protection groups are for more BT site take action, most BT users and developers argued the accused BT site is unwise, like selling chopper should not for someone used a chopper ault behavior is same, BT site itself should not for infringement behavior.

BT use hints

Recommended BT software has utorrent, Bitcomet, Azureus, these software frequently updated to provide better BT agreement support and function expansion.

Don't try to limit BT software upload speed limit, it will affect your download.

Avoid using BT default listening socket, these ports may have been service provider shielding. Use a firewall users may need in fire prevention wall open BT listening socket

Use the router users generally need through port mapping, or DMZ function, or UPNP function, make inbound request can reach use BT software on the computer.

Even finished downloads, also please try not to immediately closes BT software or make BT software stop upload, your upload BT, of the whole network of important contribution, BT network hold a certain uploading number to make BT healthy

Even without see publishers and download obligated emergence also please be patient, it may be a larger population, use what you have been assigned to the connection of group does not contain publishers and download completed, the other side USES the super - seed mode, publishers and download hide themselves who may temporarily referral.

BT principle:

Ordinary HTTP/FTP download using TCP/IP protocol, BitTorrent protocol is architecture TCP/IP protocol on a P2P file transfer protocol, TCP/IP structure in the network. BitTorrent agreement itself also contains a lot of specific content agreement and expand agreement, and in constant expansion.

According to the agreement, file publishers BitTorrent according to want to distribute files generated. The file, provide a seed file, also is referred to as the "seeds".

The file is essentially a text file, including phrases information and documents information in two parts. Phrases information is primarily BT download in need of phrases server address and phrases server Settings for file information is based on the calculation of the target file generation, the calculation results BitTorrent agreement according to within the B encoding rules coded. Its main principle is the need to provide downloadable files virtual into equal pieces, block size must 2k integer 4k for (due to the hard disk is virtual block, does not create each block documents), and each piece index information and Hash verification code into the file;. So,. The file is to be downloaded file "index". Downloaders will download file content and needs to get the corresponding. The files, and then use BT client software to download.

Download, BT client first analytical. The documents are phrases address, and then connect phrases server. Phrases server response downloaders request, provides downloaders other downloaders (including publishers) IP. Downloaders connect other downloaders, according to the document, both respectively. Other told himself already some pieces and then exchange each other without data. There is no need to other server participation, spread a single line of data flow, so reducing the server burden.

Downloaders every time they got a piece, need to figure out the download block Hash verification code. The files are compared with the same show piece, if correct, different requires to download this piece. This regulation is in order to solve the problem of the accuracy of the download content.

General HTTP/FTP download, distributing files only in a or certain servers, download person is too much, server bandwidth easily be load, become very slowly. While BitTorrent agreement download characteristics are, the more people download and provides bandwidth is more also, seed will more and more, download speed is faster.

While some people download finish off after download a task, provide less data for other users, to avoid this kind of behavior in unofficial BitTorrent agreement, existing in the super seeds algorithm. This algorithm allows the documents issued by publishers take steps files, publishers don't need a provides file all content, but slowly open download content proportions, extend the download time. At this time, fast because the person not download must provide others data, slow people have more opportunities to get the data.

Thus often caused in using the 99%, download task 1G tasks to upload 3G.

Note:

Sometimes with bt will slowly