Patent ID: 7583601
Filing Date: 2009-09-01
Classification: H04L

Abstract:
1. A method of setting multicast transfer routes in a multicast network comprising a plurality of points, the multicast transfer routes connecting a given starting point and a plurality of ending points, the multicast network comprising a multicast transfer apparatus provided to each point, a multicast transfer route computing apparatus that computes the multicast transfer routes, and a multicast transfer route setting apparatus that sets the computed multicast transfer routes, the method comprising the following steps: the multicast transfer apparatus measures a traffic state of each direction in which data flow through each link of the network and requests the multicast transfer route computing apparatus to compute multicast transfer routes by transmitting the measured traffic state; the multicast transfer route computing apparatus computes a shortest route with respect to delay connecting the starting point and the ending points based on the measured traffic state, computes delay from each point on the shortest route at the same time, and stores the computed delay in a recording medium; the multicast transfer route computing apparatus computes a greatest delay in the data flow through the computed shortest route; the multicast transfer route computing apparatus compares the greatest delay with a predefined delay condition, re-defines the delay condition if the greatest delay does not satisfy the delay condition, searches, if a condition that the shortest route satisfies is found, a partial route in the computed shortest route that has two of the same kind or different kinds of the starting point, the ending points, and branching points, as ending nodes of the partial route, that has none of the starting point, the ending points, and branching points in the middle, and that incurs the greatest cost, removes the searched partial route from the computed shortest route thereby to divide the multicast transfer route into two route trees, and sets a route computed separately as a complementary route that complements the removed route to connect the two route trees; the multicast transfer route computing apparatus informs the multicast transfer route setting apparatus of the result of computation; and the multicast transfer route setting apparatus sets the multicast transfer route in accordance with the informed result of computation.