Application Layer Multicasting Overlay Protocol a NARADA Protocol
The conventional wisdom has been that Network Layer Internet protocol(IP) is the natural protocol layer for implementing multicast related functionality but it is still plagued with concerns pertaining to scalability, network management, deployment and support for higher layer functionality such as error, flow and congestion control. In this context, an alternative architecture is, Application layer multicast (End Systems Multicasting), where at Application layer, implements all multicast related functionality including membership management and packet replication. This shifting of multicast support from routers to end systems has the potential to address the most problems associated with IP multicast. In Application-layer multicast, applications arrange themselves as a logical overlay network and transfer data within the overlay network (between end hosts). In this context, we study these performance concerns in the context of the NARADA protocol (an application layer multicasting protocol). In Narada, end systems self-organize into an overlay structure using a fully distributed protocol. We present details of NARADA and evaluate it using NS-2 simulations. Our results indicate that the performance penalties are low both from the application and the network perspectives. We believe the potential benefits of transferring multicast functionality from routers to end systems, significantly outweigh the performance penalty incurred.
