However, the increase in the number of viewers, along with the rise in a number of other online applications, has made this architecture ineffective because of bandwidth bottleneck issues. One solution introduced to solve this problem is peer to peer (P2P) technology, wherein peers automatically relay streams to other peers. The P2P network they are connected to performs an algorithm that helps peers ﬁnd a relay for a speciﬁed stream to connect to.
In multimedia streaming service, the important factors to observe are playing time and network bandwidth utilization. The purpose of this report is to present a solution to these issues. The proposal is to utilize P2P caching service that exploits the proximity of connected clients, i.e. the temporal and spatial locality of cached streams to the clients. In this scheme, connected peer clients not only receive multimedia streams from a server but also send cached streams to peer clients like a proxy server upon request. One P2P technology that can support this architecture is called inter-overlay optimization.
Figure 1 shows the different approaches employed in multimedia streaming starting from the centralized client-server topology to decentralized schemes, which includes IP multicast and P2P solutions. P2P can be further sub-divided into mesh-based, tree-based and hybrid overlays.
Each peer can accept media data from multiple parents as well as provide services to multiple children (both parent and child are relative terms in place of master-slave relationship). The advantages of this solution are high resource utilization and fast discovery of fresh peers in a single mesh due to gossiping. The disadvantages are: quality of service cannot be guaranteed due to gossiping among peers and large buffer space needed to reduce the impact of autonomy of peers (in a dynamic environment). Example applications are Coolstreaming, Promise, and GNUStream.
Each peer communicates only with one parent (per overlay) and provides service to a number of children such that a “tree” topology is always maintained (in an overlay). The advantages of this solution are: closely resembles original IP multicast ideas and low management overhead.