Dynamic DR election for generating the multicast tree in PIM‐SM

In IP multicast streaming, PIM-SM (protocol independent multicast sparse-mode) is now becoming the mainstream. However, it may happen that the optimal tree cannot be generated, depending on the location of the DR (designated router, which is the router used to generate the tree and so on when there are multiple PIM-SM routers in the segment) in some special topology. The means of handling such a situation is described only ambiguously in the PIM-SM specification. Consequently, various problems now arise in implementation. This paper considers the dynamic determination of a DR that can generate the optimal tree even in such a special topology, and proposes a new additional protocol. Tree generation for various topologies is examined for the proposed method and the existing implementation, and it is shown that the proposed method is effective for any existing topology. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 87(4): 65–72, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10105