peer-to-peer - Computer Definition
Descriptive of a relationship between equals. A peer-to-peer architecture is a network design based on computers that share the same responsibilities and use the same programs to communicate. Machines operating in such a network communicate with each other as equals, with each acting as a server for the others. Such a network differs markedly from a client/server network, where some machines are designated as servers to serve the needs of client machines. A peer-to-peer network is also markedly different from a network characterized by master/slave relationships between machines. See also client/server and master/slave.
Architecture permitting hardware and software to work on a network without central servers It is frequently used to set up home computer networks, for which a dedicated server can be too costly; it became popular with software applications such as Napster.
A controversial tool for P2P communications is known as Skype, an encrypted Internet telephony system allowing for the swapping of files; it interconnects with the publicly switched telephone system. Skype is controversial and a headache for enterprises, because it can easily penetrate firewalls; however, businesses can implement safeguards by, for example, placing Skype on a separate, dedicated segment of their network.
Released in 2004 by the makers of KaZaA, Skype scans the Internet searching for a supernode (by definition, other users running the software and, therefore, not being screened by firewalls). An unknown quantity of supernodes links to other supernodes, eventually looping back to Skype’s servers, thus allowing users on the Internet to send and receive files.
Skype is marketed as having communications encrypted with a 256-bit encryption standard, and keys are exchanged with the RSA encryption algorithm. Unlike other, nonproprietary Voice Over Internet protocols (VoIP), Skype uses a proprietary, secret protocol. So, for financial and health institutions required by law to monitor the communications between their employees and their clients, they need to be aware that Skype is unmonitorable. Skype appears to be more secure than cell phones having their encryption disabled or landlines having zero encryption. With Skype, even large files of 100MB size can be sent without contending with server size restrictions.
In recent years, the P2P abbreviation has taken on another meaning “People-to-People.” Thus, P2P (or People-to-People) has become a marketing abbreviation for selling P2P software and for creating businesses that can help individuals on the Internet to meet one another or to share some common interests.
About, Inc. P-2-P. [Online, 2004.] About, Inc. Website. http:// compnetworking.about.com/library/glossary/bldef-p2p.htm; Garfinkel, S. Can 9 Million Skype Users Be Wrong? [Online, March 22, 2005.] CXO Media Inc. Website. http://www .csoonline.com/read/030105/machine.html.
From user to user. Peer-to-peer implies that either side can initiate a session and has equal responsibility. Peer-to-peer is a somewhat confusing term, because it has always been contrasted to a central system that initiates and controls everything. But in practice, two users on a peer-to-peer system often require data from a third computer. For example, the infamous Napster file sharing service was always called a "peer-to-peer network," but its use of a central server to store the public directory made it both centralized and peer-to-peer. The two major categories of peer-to-peer systems are for file sharing (see peer-to-peer network) and CPU sharing (see grid computing). In a wireless network, a peer-to-peer architecture is called an "ad hoc" network (see mobile ad hoc network). There are many applications and services that claim to be peer-to-peer. Visit www.openp2p.com and click on the "P2P Directory" for a comprehensive list of resources, articles and blogs about the subject.