| Summary: | 碩士 === 國立交通大學 === 網路工程研究所 === 103 === In transmitting streaming with multicast trees, multiple shared trees can relieve the load in a single rendezvous point (RP) and construct shorter paths compared with single shared tree. On the other hand, compared with per-source trees, multiple shared trees can reduce the number of trees. Thus, this thesis presents an approach called Multiple Shared Trees with Locality (MSTL) to construct multiple shared trees in software defined networking (SDN). Constructing multiple shared trees in SDN is more suitable than that in the traditional networks because the controller being a centralized handler can burden all overhead at constructing trees. In MSTL, the controller first clusters the near multicast sources into a few clusters according to a predefined distance threshold, then selects a center switch, which has the minimum distance to all sources, as RP for each cluster, and finally constructs a multicast tree with shortest paths. In additional, the controller inserts aggregative flow entries into on-tree switches to reduce the amount of flow entries. Emulations on the Ryu controller and the Mininet emulator show that constructing between 2 to 6 trees. The computation time of MSTL is about 100 ms, much less than hundreds ms required in per-source tree. Moreover, MSTL only requires 2300 flow entries, 4% of that with per-source tree in a large topology. Finally, MSTL achieves the initial latency of 120 ms in a small topology.
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