A route optimization algorithm and its application to mobilelocation management in ATM networks

摘要

In this paper, we propose an algorithm for optimizing the route ofna connection that becomes suboptimal due to operations such as handoffsnand location-based reroutes, for mobile ATM (asynchronous transfer mode)nnetworks based on the PNNI (private network-to-network interface)nstandard. This algorithm uses hierarchical route information of thenconnection and summarized topology and loading information of thennetwork to determine a “crossover node” such that adjustingnthe connection from that crossover node results in an optimally routednconnection. We then apply this algorithm to the mobile locationnmanagement problem. Location management schemes have been proposed innwhich an incoming call to a mobile is first routed to its home switchn(based on summarized reachability data) and then rerouted to thenmobile's current location. If we consider such rerouting a “firstnphase” of mobile connection setup, a “second phase” isnrequired to optimize the paths of such rerouted connections. Such annapproach is considered a two-phase mobile location/connection setupnscheme. Alternatively, an incoming call to a mobile can be first routednto its home switch based on summarized reachability data, and thenn“cranked back” to an optimal crossover node before reroutingnthe connection to the mobile's current location. Such a scheme is anone-phase mobile location/connection setup scheme since it directlynresults in an optimal path. A comparative performance analysis of thenone- and two-phase connection setup schemes is presented. Measures ofncomparison are call setup delay and the amount of network resourcesnallocated to a connection. The maximum call setup delay (worst case callnsetup delay) is lower in the two-phase scheme, but the average callnsetup delay is lower in the one-phase scheme. The amount of resourcesnrequired for a connection in the two-phase scheme (prior to routenoptimization) is significantly greater than that in the one-phase scheme