As a new optical network architecture that can be built with currently available devices and can achieve bandwidth allocation with granularity finer than a wavelength, the light-trail architecture attracts attention. For the light-trail architecture using token passing medium access control, the split trail architecture is proposed for improving the throughput. In the architecture, a trail is split into the upstream trail and the downstream trail at the token holding node and independent data transmissions on the two trails are permitted. However, the split trail architecture leaves the bandwidth of links upstream of the upstream-token holding node idle because the split of the trail is driven by the reception of only the downstream-token. In this paper, we propose the multi-split trail architecture for further improving the throughput. Our architecture utilizes the idle bandwidth by splitting the trail driven by the reception of both upstream- and downstream-tokens. We formulate the decision problem of the traffic accommodation where we optimize the token holding times so that the input traffic is successfully accommodated, as a linear programming problem. Then, we derive the maximum effective throughput of the multi-split trail architecture by solving the problem, and investigate the degree of improvement over the split trail architecture. According to numerical examples, the multi-split trail architecture achieves 1) the same maximum effective throughput as the split trail architecture for an uniform traffic pattern where every node pair has the same sending rate, and 2) about 1.93 times as high maximum effective throughput for its favorite traffic pattern where every transmission node sends data to its adjacent downstream node only and their rates are identical.
