Directed Trees in Multicast Routing

Maria João Nicolau, António Costa, Alexandre Santos and Vasco Freitas

Universidade do Minho
Departamento de Informática
P-4710-057 Braga, Portugal

Tel.: +351 253 604470
Fax.: +351 253 604471
E-mail: joao (at), {costa,alex,vf} (at)


Traditional multicast routing protocols use RPF (Reverse Path Forwarding) concept to build multicast trees. This concept is based upon the idea that an actual delivery path to a node is the reverse of the path from this node to the source. This concept fits well in symmetric environments, but in a routing environment where Quality of Service is considered the guarantee that a symmetrical path will exist between two network addresses is broken. Available network resources impose specific Quality of Service asymmetries, therefore reverse path routing may not be used. In this paper a new multicast routing strategy is proposed, enabling directed trees establishment, instead of reverse path ones. This new strategy, DTMP- Directed Trees Multicast Routing, is then implemented and simulated using Network Simulator. Simulation results, driven from several scenarios are presented, analyzed and compared with PIM-SM.

The 2nd International Workshop on QoS in Multiservice IP Networks (QoS-IP 2003), Milano, Italy, May 24-26, 2003       LNCS, vol 2601, pp. 320-333, Springer-Verlag, 2003