Explicit multicasting within a unicast infrastructure

Explicit multicasting (xcasting) is a type of multicasting that allows packets to be addressed to multiple destinations. Unfortunately, special routers and hosts for replicating and directing these packets are typically needed to deploy xcasting. One alternative approach to deployment is to use devices that can examine packets queued at routers and recode unicast traffic as xcast traffic. These devices allow xcasting to be added to the Internet incrementally and can optimize existing unicast traffic without requiring changes to existing hosts or applications. Simulations show that this type of xcasting performs well in reducing bandwidth usage and can even reduce network latency in certain situations. Although traditional multicasting offers superior scalability to xcasting, xcasting has many appealing properties worthy of further examination.