The QuORRUM protocol: efficient tree repair for qualification-based multicast

Increasing sophistication of Internet services requires more refined methods of service differentiation in the delivery of data and media flows. Earlier work on quality-of-service (QoS) routing has focused on the network mechanics to find the best path for admitted connections under specific QoS constraints, and to maximize global resource utilization. We look at the related notion of qualification-based routing, where routers check on the fulfillment of one or more constraints before handling a particular packet flow. Packets are demarcated and evaluated by qualifiers in their headers, which may indicate for example an authorization level in secure transmissions, or a payment receipt for a media-on-demand application. In particular, this paper explores the coordinative processes for tree formation and repair in qualification-based multicast routing, with the goal to leverage group-centric communication for future mass media Internet applications. We introduce the QuORRUM protocol to implement qualifier-driven sparse-mode tree building and repair and show that it performs better than other protocols in terms of bandwidth usage and repair times