Introduction to Peer-to-Peer Networking

Peer to peer is an approach to computer networking where all computers share equivalent responsibility for processing data. Peer-to-peer networking (also known simply as peer networking) differs from client-server networking, where certain devices have responsibility for providing or "serving" data and other devices consume or otherwise act as "clients" of those servers.

Characteristics of Peer-to-Peer Network

- A P2P network can be an ad hoc connection—a couple of computers connected via a Universal Serial Bus to transfer files.
- A P2P network also can be a permanent infrastructure that links a half-dozen computers in a small office over copper wires.
- A P2P network can be a network on a much grander scale in which special protocols and applications set up direct relationships among users over the Internet.
- P2P software systems like Kazaa and Napster rank amongst the most popular software applications ever.
- P2P technologies promise to radically change the future of networking. P2P file sharing software has also created much controversy over legality and "fair use."
- A P2P network implements search and data transfer protocols above the Internet Protocol (IP).
- To access a P2P network, users simply download and install a suitable P2P client application.

A P2P setup can facilitate the following:
- Sharing of file by all the users of the network.
- Telephony.
- Media streaming - both audio and video.
- Community/discussion forums.

Types of P2P Networks

The P2P networks are normally classified as either ‘pure’ or ‘hybrid’ types.
Pure Networks
- Peers have got to be equals – no single node can supersede or dictate terms over another.
- There is no requirement of a central server and as such, no possibilty of a client-server correlation.
- There is also no need for a central router.

Hybrid P2P Networks
- This type of network needs to have a central server that can store data on all the peers and deliver it whenever asked to do so.
- The route terminals are treated as addresses, each one of which can be referenced by a specfic set of indices.
- Since the central server is not supposed to have any kind of resources available to it, the peers themselves are required to host all the resources. As and when required, a peer informs the central server about the type of resource to be shared and the details of the peer/s who should be allowed to share it.

Benefits of P2P Networks

1. Efficient use of resources.
- Unused bandwidth, storage, processing power at the edge of the network.
2. Scalability
- Consumers of resources also donate resources.
- Aggregate resources grow naturally with utilization.
3. Reliability
- Replicas.
- Geographic distribution.
- No single point of failure.
4. Ease of administration
- Nodes self organize.
- No need to deploy servers to satisfy demand (c.f. scalability).
- Built-in fault tolerance, replication, and load balancing.