We propose a measurement-based routing algorithm to load balance
intradomain traffic along multiple paths for multiple multicast   
sources. Multiple paths are established using application-layer
overlaying. The proposed algorithm is able to converge under
different network models, where each model reflects a different
set of assumptions about the multicasting capabilities of the
network. The algorithm is derived from simultaneous perturbation
stochastic approximation and does not assume that the gradient of
an analytical cost function is known to the algorithm, but rather
relies on noisy estimates from measurements. Using the analytical
model presented in the paper we prove the convergence of the
algorithm to the corresponding optimal solution under each network
model. Simulation results are presented to demonstrate the
additional benefits obtained by incrementally increasing the
multicasting capabilities. We also provide a comparative study 
with the well-known IP multicast algorithm DVMRP.
UMIACS-TR-2004-45