What is peer-to-peer (P2P)? How P2P networks are used

A peer-to-peer network is a group of devices that can share resources with each other. The model is common in small businesses. So exactly what is a peer-to-peer network? How does the P2P model work? Read the article below from Mona Media to learn more about this model.

What is peer to peer?

P2P is a distributed application model that splits tasks and workload among peers. Peers are the devices taking part in the application, with equal privileges. Together they form a network of equal nodes.

What can peer to peer do? P2P provides an environment for parallel computing, distributed storage and anonymous routing of network traffic. Its best-known ability is sharing media. That same ability is also why P2P is often used for copyright infringement.

Users have full control of the operating parameters when using P2P applications. For example, it can let many members connect at once, or provide services, systems and protection resources for the network.

The peer-to-peer model

P2P topologies have been around since the days of ARPANET, but the model only became popular in 1990. Read on to understand more about peer to peer.

Routing and resource discovery

A P2P network builds an overlay network on top of the physical network topology. The nodes of the physical network form a subset of the nodes in the overlay. Data is still exchanged directly over the TCP/IP network, but at the peer-to-peer application layer, data communicates directly through logical overlay links.

The overlay is used to index and discover peers. It also makes the peer-to-peer system independent of the physical network topology. Depending on how nodes link to each other in the overlay and how resources are located and indexed, P2P networks fall into 2 main types: unstructured networks and structured networks (or a mix of the two).

Unstructured networks

An unstructured peer-to-peer network means the overlay is not designed around any framework. It is made of nodes that form random links with each other. Some unstructured P2P models are Gnutella, Gossip and Kazaa.

Because no structure is imposed on the whole network, these networks are very easy to build. They also allow optimization for different geographic regions. In general, unstructured networks are strong and cope well with a high "churn" rate. Churn is when a large number of peers frequently join and leave the network.

Unstructured networks also have many limits because of this lack of structure, especially when a peer wants to find a particular piece of data on the network. The search query has to be flooded across the network to reach as many peers sharing the data as possible. Flooding often creates a large amount of signaling traffic and uses more CPU. Above all, there is no guarantee that every query will be resolved.

Structured networks

What is the structured peer-to-peer model? It is a model where the overlay is organized and run as a specific topology. The structure ensures that any node can find files and resources easily. Even extremely rare resources are found quickly.

Today, the most common structured P2P networks use a DHT (Distributed Hash Table). A variant of consistent hashing assigns ownership of each file to a particular peer. This lets peers look up resources on the network using a hash table. In other words, key-value pairs are stored in the DHT, and any participating node can retrieve the value linked to a given key.

Hybrid models

Hybrid models combine the client-server model and the peer-to-peer model. A common hybrid has a central server that helps peers find each other. This structure balances the centralized functions of a structured server/client network with peer-to-peer. Many hybrid models are in use in practice, and Spotify is a typical example.

Today, hybrid models are rated higher in performance than unstructured networks. This shows in key functions such as search, which needs centralized functions but benefits from the decentralized nodes that an unstructured network provides.

CoopNet content distribution system

CoopNet, or cooperative networking, is a system that offloads servers by having peers that recently downloaded content serve it to others. The network was proposed by computer scientists Venkata N. Padmanabhan and Kunwadee Sripanidkulchai, who worked at Microsoft Research and Carnegie Mellon University.

The CoopNet content distribution system can take load off a server. When a server is overloaded, it redirects requests to peers that have agreed to mirror that content.

Pros and cons of P2P

Advantages

• A peer-to-peer network does not need a server.
• Each computer is managed by its own user.
• Operating P2P does not require any complicated specialist knowledge.
• Homes and small businesses are a good fit for a P2P network.
• It does not need much network traffic.

Disadvantages

• Information on the machines cannot be backed up centrally.
• If many computers access the network at the same time, performance drops.
• Data files are not organized systematically but kept on personal computers. This makes them noticeably harder to locate.
• It only offers a few basic permissions, and security is poor.

Uses of peer to peer

A peer-to-peer network treats server and client as equals. The system is kept running by a distributed network of users. The devices running the software act as intermediaries for sharing data. When users find and download files, they can send them on to another device on the network.

Some industries that use peer-to-peer networks include:

• Cryptocurrency: Bitcoin, Ethereum and more.
• Home rentals (homesharing).
• Financial lending (P2P lending).
• Online marketplaces.
• File sharing.
• Open-source software.

That is the information related to what a peer-to-peer network is. We hope it helps you understand what peer to peer is, and gives you more knowledge and a clearer view of peer-to-peer networks.

>>> Learn more: What is a LAN? How does a LAN work?