Study on the Delay-constrained Multicast Issue in VPLS Networks
VPLS中具有时延约束机制的组播问题研究

VPLS has gained world-wide recognition in recent years. However, deploying VPLS in Metro is confronted with one complicated issue: the multicast problem. Instead of solving the NP-Complete Steiner tree problem, this paper emphasizes more on the experiential and implemental aspect of multicast in VPLS network. It begins with the construction of least cost tree(LCT) and least delay tree(LDT), then an iterative algorithm is proposed to construct all the delay-constrained candidate trees, the one with least cost is chosen. To avoid unwanted traffic sent to PE devices, a pruning mechanism is also suggested. Compared with Steiner solutions, the algorithm is more suitable for implementation as the time complexity is only O(n~2). Simulation result shows that the algorithm is feasible and suitable in building delay-constrained multicast trees over VPLS domain.