點對點

出自KMU Wiki

一點對點 （或“ 點對點 ” ） 計算機網絡使用不同的參與者之間的連接在一個網絡和累積帶寬的網絡參與者，而非傳統的集中資源，相對較低的服務器的數量提供的核心價值，以一個服務或應用。 P2P networks are typically used for connecting nodes via largely ad hoc connections. P2P網絡通常用於連接節點 ，主要是通過特設的聯繫。 Such networks are useful for many purposes.這種網絡是有益的多種用途。 Sharing content files (see file sharing ) containing audio, video, data or anything in digital format is very common, and realtime data, such as telephony traffic, is also passed using P2P technology.共享內容的文件（見文件共享 ） ，其中載有音頻，視頻，數據或任何的數字格式是很普遍的，實時數據，如電話的交通，亦是通過使用P2P技術。

A pure P2P network does not have the notion of clients or servers, but only equal peer nodes that simultaneously function as both "clients" and "servers" to the other nodes on the network.一個純粹的P2P網絡沒有概念的客戶端或服務器，但只有平等的同儕 的節點功能，同時作為“客戶”和“服務器”到其他節點上的網絡。 This model of network arrangement differs from the client-server model where communication is usually to and from a central server.這種模式的網絡安排不同，從客戶端-服務器模式的溝通通常是和從一個中央服務器。 A typical example of a file transfer that is not P2P is an FTP server where the client and server programs are quite distinct, the clients initiate the download/uploads, and the servers react to and satisfy these requests.一個典型例子，文件傳輸，這不是P2P的是一個FTP伺服器客戶端和服務器程序是相當明顯的，客戶開始下載/上傳，和服務器的反應並滿足這些要求。

The earliest P2P network in widespread use was the Usenet news server system, in which peers communicated with one another to propagate Usenet news articles over the entire Usenet network.最早的P2P網絡在廣泛使用是的Usenet 新聞服務器系統，在其中同儕溝通，互相宣傳的Usenet新聞文章在整個新聞組網絡。 Particularly in the earlier days of Usenet, UUCP was used to extend even beyond the Internet .特別是在較早前天的Usenet ， uucp被用來延長，甚至超越了互聯網 。 However, the news server system also acted in a client-server form when individual users accessed a local news server to read and post articles.不過，新聞服務器系統也採取行動，在客戶端-服務器的形式，當個別用戶進入本地新聞服務器的閱讀和張貼文章。 The same consideration applies to SMTP email in the sense that the core email relaying network of Mail transfer agents is a P2P network while the periphery of Mail user agents and their direct connections is client server.同樣的考慮適用的SMTP電子郵件，在意義上說，核心的電子郵件中繼網絡， 郵件傳輸代理是一個P2P網絡，而周邊的郵件用戶代理和他們的直接連接是客戶端服務器。

Some networks and channels such as Napster , OpenNAP and IRC server channels use a client-server structure for some tasks (eg searching) and a P2P structure for others.一些網絡和渠道，如Napster ， opennap和IRC 服務器的渠道，使用客戶端-服務器結構的一些任務（如搜索）和一個P2P結構等。 Networks such as Gnutella or Freenet use a P2P structure for all purposes, and are sometimes referred to as true P2P networks, although Gnutella is greatly facilitated by directory servers that inform peers of the network addresses of other peers.網絡，如gnutella或freenet使用一個P2P結構的所有目的而言，有時被稱為真正的P2P網絡，雖然gnutella是大大促進了目錄服務器告知同行的網絡地址，其他同儕。

P2P architecture embodies one of the key technical concepts of the Internet, described in the first Internet Request for Comments , RFC 1 , "Host Software" dated 7 April 1969 . P2P的架構，體現了其中的關鍵技術的概念，在互聯網上，介紹了在第一次互聯網徵求意見 ， 符合RFC 1 ， “主機軟件” 4月7日的 1969年 。 More recently, the concept has achieved recognition in the general public in the context of the absence of central indexing servers in architectures used for exchanging multimedia files.最近，這一概念已取得承認在一般公眾語境中的情況下，中央索引服務器在架構用於交換多媒體文件。

The concept of P2P is increasingly evolving to an expanded usage as the relational dynamic active in distributed networks, ie not just computer to computer, but human to human. Yochai Benkler has coined the term "commons-based peer production" to denote collaborative projects such as free software.概念的P2P是越來越演變，以擴大使用作為關係動態，積極在分佈式網絡，即不只是電腦對電腦，但在人與人之間。 yochai勒已創造了術語“的商品，基於同儕生產”是指協作項目等作為免費軟件。 Associated with peer production are the concept of peer governance (referring to the manner in which peer production projects are managed) and peer property (referring to the new type of licenses which recognize individual authorship but not exclusive property rights, such as the GNU General Public License and the Creative Commons licenses).與同儕生產的概念，同儕的管治（指以何種方式同儕的生產性項目管理）和同儕的財產（指新型執照承認個別作者，但不是排他性的財產權利，如GNU通用公共許可和在Creative Commons許可） 。

分類

P2P網絡可分為什麼，它們可以用來為：

file sharing文件共享
telephony電話
media streaming (audio, video)流媒體（音頻，視頻）
discussion forums討論論壇
Other classification of P2P networks is according to their degree of centralization.其他分類的P2P網絡是根據其程度的集中。

In 'pure' P2P networks:在'純'的P2P網絡：

Peers act as equals, merging the roles of clients and server同儕作為平等的，合併的角色，客戶端和服務器
There is no central server managing the network是沒有中央服務器管理網絡
There is no central router有沒有一個中央路由器
Some examples of pure P2P application layer networks designed for file sharing are Gnutella and Freenet .一些例子，純的P2P 應用層網絡的設計文件共享是gnutella和freenet 。

There also exist countless hybrid P2P systems:還存在著無數的混合P2P系統：

Has a central server that keeps information on peers and responds to requests for that information.有一個中央服務器不斷的資料，同儕回應請求這方面的資料。
Peers are responsible for hosting available resources (as the central server does not have them), for letting the central server know what resources they want to share, and for making its shareable resources available to peers that request it.同儕是負責主辦可用的資源（如中央服務器沒有他們） ，為讓中央服務器知道什麼樣的資源，他們想要分享，並作出自己的共享資源提供給同行請求。
Route terminals are used addresses, which are referenced by a set of indices to obtain an absolute address.路線終端使用地址，這是參照了一套指數，從而取得絕對地址。
eg例如：

Centralized P2P network such as Napster集中式P2P網絡，比如Napster
Decentralized P2P network such as KaZaA分散的P2P網絡Kazaa等
Structured P2P network such as CAN結構的P2P網絡，例如可以
Unstructured P2P network such as Gnutella非結構化的P2P網絡，如gnutella
Hybrid P2P network (Centralized and Decentralized) such as JXTA (an open source P2P protocol specification)混合P2P網絡（集中和分散） ，如JXTA技術 （ 1開放源代碼的P2P協議規範）

優勢

一個重要的目標在P2P網絡是所有客戶端提供的資源，包括帶寬 ，存儲空間，和運算能力。 Thus, as nodes arrive and demand on the system increases, the total capacity of the system also increases.因此，作為節點到達和需求，對系統的增加，總系統的容量也增加了。 This is not true of a client-server architecture with a fixed set of servers, in which adding more clients could mean slower data transfer for all users.這是不正確的客戶-服務器架構與一套固定的服務器，在其中加入更多的客戶可能意味著較慢的數據傳輸為所有用戶。

The distributed nature of P2P networks also increases robustness in case of failures by replicating data over multiple peers, and -- in pure P2P systems -- by enabling peers to find the data without relying on a centralized index server.分佈式的性質， P2P網絡也增加了魯棒性，在案件的失敗是由複製數據在多個同行和-在純粹的P 2P系統-讓同儕找到的數據而不必依賴中央索引服務器。 In the latter case, there is no single point of failure in the system.在後一種情況下，是沒有單點故障在該系統。