Most of the content delivery services are built on set of servers deployed in clouds. As major disadvantage of this approach is the cost of bandwidth for a wide client audience. Other drawbacks are complex set up and deploy, streaming servers saturation during traffic spikes and etc.
A P2P approach comes to solve many of the problems using peers by collaborating with each other. All peers are building an overlay network of multiple nodes, on the top of IP layer. The decentralized nature of this overlay network has no predefined hierarchy. A node in P2P network can be a seed or leech. A seed is used to point a node who has all the content available. A seed accepts incoming connections from leeches who request the content (leeches do not have the full playable stream).
Here are P2P main features:
• Fully distributed: nodes in the network are self-dependent which solves unique point of failure problem.
• Scalable: the size of the network grows according to the amount of current live users.
• Maintenance: the network is self-organized using a membership management algorithm.
• Greater reach: across the world, especially where CDN points of presence are more scarce.
• Better QoS: the segments come from the source that can provide them most quickly.
Nowadays we can see a collaboration bewtween P2P and CDN a.k.a Hybrid CDN-P2P Architecture, “serverless” CDN or PCDN. This supplementation apparently results in a more affordable user experience. PCDNs use a different type of fragmentation to distribute data called P2SP technology – Peer To Servers and Peers. P2SP generally works in a closed manner by only utilizing its private owned servers to accelerate its private organized peer swarms.