Shared-Tree selection method for aggregated multicast
Yusuke Sekine, Taiju Mikoshi, Toyofumi Takenaka · 2012
Aggregated multicast methods have been proposed in order to reduce the size of routing tables in routers for multicast communications, where plural multicast sessions share a single multicast tree called Shared-Tree. STA (Scalable-Tree-Aggregation) method has been proposed as a Shared-Tree selection method, where a minimum size Shared-Tree has been selected among Shared-Trees which contain all destination nodes of a multicast session. In the STA method, the selected Shared-Tree sometimes contains invalid destination nodes for the multicast session and causes the unnecessary traffic load. In this paper, we proposed a novel Shared-Tree selection method which makes it possible to select smaller size Shared-Tree compared with the multicast session by a grafting method. By the grafting method, destination nodes not involved in the selected Shared-Tree can be connected to the Shared-Tree. We can expand the search range of Shared-Trees by the grafting method and select a Shared-Tree, destination nodes of which overlap those of the multicast session as many as possible. In our proposed selection method, Shared-Trees are selected by the measurement of overlapping degree, which indicates how many destination nodes in the multicast session overlap with those in Shared-Trees. Moreover, we introduce a replacement method for reducing the entry size of Shared-Trees. We evaluate our selection method by simulation experiments and show the effectiveness of our proposed method.