Towards multi-class based multicast routing

While Differentiated Services reach maturity, and a few per hop aggregate behaviors are being standardized, little efforts are being carried out to enforce class differentiation by selecting alternative routes. Within a differentiated services multicast scenario, multiple multicast forwarding trees must be found, one per Class of Service (CoS), in order to comply with different per-class Quality of Service (QoS) requirements. This paper presents a new multicast routing protocol enabling per class multicast tree computation. The proposed heuristics enable directed trees establishment, instead of reverse path ones, due to the importance of link asymmetry within an environment which is, essentially, unidirectional. The main assumption supporting this work is that a per class path computation may well complement, at routing level, node level differentiation techniques, thus providing per class differentiated handling. The strategy presented is also useful for network traffic engineering as it potentially enables traffic distribution along different network links.