Showing papers on "Equal-cost multi-path routing published in 1984"

Datagram routing for internet multicasting

Abstract: We present a solution to the problem of multidestination routing in internetworks. The component subnets of these internets share a common datagram internet layer, and the gateways and hosts can determine the next gateway en route to a foreign net. Our datagram routing offers high resilience to network failures, major reductions in network traffic, and no changes whatsoever to the subnetwork routing. The routing follows “shortest” paths as defined by the distance criteria of an internet. We intend to use the algorithm as an option of the DoD Internet Protocol with only minor changes to IP while preserving interoperability with IP modules not supporting multidestination.

Three-Layer Channel Routing

Abstract: With the advent of VLSI technology, multiple-layer routing becomes feasible. Two special types of three-layer channel routing, VHV and HVH, are introduced in this paper. The merging algorithm and the left edge algorithm used in two-layer routing can be extended to three layers. Attempts are made to compare the lower bounds of channel width of three types of routing--two-layer, VHV, and HVH. The algorithms were coded in PASCAL and implemented on VAX 11/780 computer. The computational results are satisfactory, since all the results lead to a further reduction in routing area.

Alternate paths in a self-routing packet switching network

Abstract: A packet switching architecture in which switching network nodes (200-206) automatically determine alternate routes through a switching network (107) so as to increase reliability and distribute traffic. The switching network comprises stages of distribution (D) and routing nodes (R). The routing nodes are responsive to physical addresses associated with the packets to communicate those packets to address designated downstream nodes. The distribution switching nodes statistically communicate packets to downstream switching nodes on the basis of an alternate routing algorithm and availability of downstream nodes. The initial network stages are alternate distribution and routing stages followed by only routing stages for the remaining stages of the network. Both the routing and the distributing nodes are identical in design and are responsive to an input signal from the network to assume either routing or distributing functions.

A Global Routing Algorithm for General Cells

Abstract: An algorithm is presented which accomplishes the global routing for a building block or general cell routing problem. A line search technique is employed and therefore no grid is assumed either for the module placements or the pin locations. Instead of breaking the routing surface up into channels, a maze search finds acceptable global routes while avoiding the blocks. Both multi-pin terminals and multi-terminal nets are accomodated. It is shown that the Lee-Moore grid-based approach is actually a special case of the general search algorithm presented. This algorithm is borrowed from the field of artificial intelligence where it has been applied to many state-space search problems.

An Efficient Channel Router

Abstract: In the LSI chip layout design, channel routing is one of the key problems. The problem is to route a spcified net list between two rows of terminals across a two layer channel. This paper presents a new routing algorithm, which is an improved version of the classical "left edge algorithm". The new algorithm uses a row by row approach, calculating an optimum net assignment to each row. The algorithm was implemented for examples in previously published papers. Experimental results show that the new algorithm produces optimum solutions in most cases.

A k-SHORTEST PATHS ROUTING HEURISTIC FOR STOCHASTIC NETWORK EVACUATION MODELS

Abstract: Stochastic-network evacuation models require an optimization process to determine the best evacuation routes for a building's occupants. The optimization process developed and applied below is a heuristic based on the K-th Shortest Path Algorithm.

Sequencial Routing Optimization for Circuit Switched Networks

Abstract: Nonhierarchical alternate routing is the simplest extension to the hierarchical routing currently used in telephone networks. In order to evaluate the merits of such a technique, it is necessary to be able to optimize some performance measure over the routing variables. In a first step, a short discussion is presented of the evaluation algorithms used for computing the end-to-end blocking probabilities in networks operating under nonhierarchicai alternate routings. Then the results of a statistical sampling of the routing space for a small network are presented, to illustrate important characteristics of the routing problem. Next, two heuristic optimization techniques are discussed, one based on classical steepest descent and the other inspired from classical routing optimization of traffic flows in transportation and communication networks. Acceleration techniques are discussed in both cases, and the convergences rates of the alorgithms are presented for a number of networks. A brief discussion is finally given of the usefulness of nonhierarchical alternate routing in reducing the blocking probability in already existing networks, and in decreasing the number of trunks required to maintain a prespecified grade of service, both in real and artificially generated networks.

Topological Routing of Multi-Bit Data Buses

Abstract: In LSI and VLSI layout, certain categories of signal nets, e.g. critical nets, power buses and data buses, require special attention during routing. In data bus routing the goal is to maximize the commonality of the routing paths comprising the bus, without unnecessarily lengthening individual routing paths. A topological data bus router has been implemented in the Hughes Automated Layout system and is the subject of this paper.

Distributed asynchronous optimal routing in data networks

Abstract: We prove convergence of a distributed gradient projection method for optimal routing in a data communication network. The analysis is carried out without any synchronization assumptions and takes into account the possibility of transients caused by updates in the routing strategy being used.

Distributed routing algorithm for a circuit packet switching network

Abstract: A distributed routing algorithm for an integrated network with circuit and packet switching capabilities is proposed. The algorithm is based on the ideas of a minimum-delay routing algorithm proposed by Gallager. The trunk organisation used in the integrated network allows a fixed or moving boundary between circuit and packet traffic. The proposed routing algorithm operates independently of the trunk management policy, and attempts to maximise a network performance measure M. This measure reflects both the end-to-end blocking for circuit traffic and the average end-to-end delay for packets. It will be shown that, for optimal performance, packet traffic must be routed in the direction of minimum incremental link delay to the packet destination. Circuit routing, on the other hand, depends on whether the trunk boundary is fixed or movable. Thus, under the fixed-boundary management policy, circuit traffic must be routed in the direction of minimum incremental link blocking to the circuit destination. Under the moving-boundary management policy, circuit routes must be chosen to minimise the effect on packet performance, i.e. minimum incremental packet delay due to incremental circuit traffic. The proposed routing algorithm has been tested for its adaptability to various load conditions. These investigations have also demonstrated the performance improvement due to the moving-boundary trunk organisation.