Triangular routing

Abstract: An ATM based routing concept for LEO intersatellite link networks is proposed. The challenges arising from the complex time-variant ISL network topology are tackled by a discrete-time network model and routing procedure. The approach is based on the combination of a modified standard routing scheme and the ATM VPC concept. The routing scheme works completely off-line, i.e. prior to system operation. In a first step, a virtual topology is set up for all successive time intervals, providing instantaneous sets of alternative VPCs (paths) between all source-destination satellite pairs. In the second step, path sequences over a series of time intervals are chosen from that according to a certain optimization procedure. Two different optimization procedures are discussed in detail, and a numerical performance evaluation is presented for telephony service in an example ISL network (Iridium). The overall routing performance is evaluated in terms of remaining delay jitter due to inevitable path handover. The results show that optimized routing strategies are specifically capable of minimizing severe delay jitter, and thus in turn reduce the complexity of ATM based operation in a connection-oriented service environment.

Abstract: An approach to adaptive routing in multirate networks using a Markov decision theoretic framework which maintains low computational complexity while still providing quite accurate routing information is proposed. In this approach, each link is modeled as a birth-death process to reduce the state space size and a policy iteration applied to achieve better network performance. The results show that routing algorithms based on this approach yield better performance than least-load path routing (LLP) without incurring any significant increase in computational complexity. >

Abstract: Since the Mobile IP is defined under the assumption that a mobile node roams between networks conforming to the same communications protocols, mobile communications between IPv4 and IPv6 are not possible. Further, a translation of the location registration messages also requires translating the format between different protocol layers. To solve this problem, a mobile proxy apparatus 2 is provided between a home network 1 a and a foreign network 1 b governed by different communications protocols. The mobile proxy apparatus 2 has a DNS-ALG function, a translator function and a Mobile IP function, and, by combining these functions, performs address translation and format translation on Mobile IP messages and user packets. The MN4 has Mobile IPv4 and Mobile IPv6 functions and executes communication suitable for the communications protocol governing the network to which it moves.