A transmission system for multicast traffic with preallocation scheme in WDM ring networks

RINGO (Ring optical) network is WDM ring network for multicast traffic. In RINGO network, a particular wavelength is assigned to each node for the packet reception and each node is equipped with fixed transmitters, which are tuned to all the wavelengths corresponding to all the destination nodes. Therefore, RINGO network can treat multicast packets efficiently. However, in RINGO network, when a traffic load is high, it hardly happens that all the wavelengths corresponding to all the destination nodes of multicast packets are available. In this research, We propose a new transmission system for multicast traffic in a WDM ring network. In the proposed system, the preallocation scheme is used for the transmission of the multicast packets and the scheme in which each node senses the status of wavelengths on each slot is used for the transmission of the unicast packets. By sending multicast packets preferentially and simultaneously with preallocation map, the proposed system can reduce the mean packet delay and the variation of the packet transmission delay. We compare the performance of the proposed system with that of the conventional one with respect to the mean packet delay by computer simulations. As a result, we find that the proposed system can reduce the mean packet delay and the variation of the packet transmission delay.