Showing papers on "Geographic routing published in 1985"

A warehouse location-routing problem

Abstract: The interdependence between distribution center location and vehicle routing has been recognized by both academics and practitioners. However, only few attempts have been made to incorporate routing in location analysis. This paper defines the Warehouse Location-Routing Problem (WLRP) as one of simultaneously solving the DC location and vehicle routing problems. We present a mixed integer programming formulation of the WLRP. Based on this formulation, it can be seen that the WLRP is a generalization of well-known and difficult location and routing problems, such as the Location-Allocation Problem and the Multi-depot Vehicle Dispatch Problem. It is therefore a large and complex problem which cannot be solved using existing mixed-integer programming techniques. We present a heuristic solution method for the WLRP, based on decomposing the problem into three subproblems. The proposed method solves the subproblems in a sequential manner while accounting for the dependence between them. We discuss a large-scale application of the proposed method to a national distribution company at a regional level.

Fault location techniques for distributed control interconnection networks

Abstract: One class of networks suitable for use in parallel processing systems is the multistage cube network. The authors focus on fault location procedures suitable for use in networks that use distributed routing control through the use of routing tags and message transmission protocols. Faults occurring in the data lines can corrupt message routing tags transmitted over them and thereby cause misrouting of messages. Protocol lines (used in handshaking between network sources and destinations), if faulty, can prevent a message path from being established or can cause the path to `lock up' once transmission of data has begun. These faults have more pronounced effects on the network performance than faults previously considered for centralized routing control systems. The single-fault location procedures presented form a logical superset to those of the centralized control systems (where message routing is dictated by the actions of a global control unit) and can be adapted for use in both circuit and packet switching networks.

Distributed Multi-Destination Routing: The Constraints of Local Information

Abstract: In computer networks, message routing is often accomplished by network nodes using local information. The unavailability of global information intuitively makes hard routing problems virtually impossible. This paper formalizes this intuition by examining a hard (NP-complete) routing problem, the problem of multi-destination routing. It is shown that with only limited information it is impossible to optimize network utilization for the multi-destination routing problem. Moreover, it is impossible to even approximate optimality to within a specific tolerance. Several versions of this result are proved; the versions differ in terms of the amount of information available at a node, and the extent to which the problem cannot be approximated. An improved local information algorithm is presented which is best possible amongst local information algorithms.

New Routing and Preemption Algorithms for Circuit-Switched Mixed-Media Networks

Abstract: New routing and preemption algorithms were developed for circuit-switched networks such as the Defense Switched Network that include both broadcast satellite and point-to-point transmission media. Three classes of routing procedures were evaluated: (1) mixed-media routing with fixed routing tables and call processing rules that included crankback and remote earth-station querying, (2) adaptive mixed-media routing which adapted routing tables after network damage, and (3) precedence flooding which routed high-precedence calls using flooding techniques. A new preemption technique called guided preemption was also evaluated. When guided preemption is used, lower precedence calls to preempt are selected after examining the paths of all calls previously routed through a switch. Call paths are added to the call-setup-success common-channel-signalling (CCS) packet at the call destination and then read in and stored within each switch in the call path as this message travels back to the call source. Tools developed to evaluate algorithms included a steady-state network analysis program, a call-by-call simulator, and the EISN testbed network described in a companion paper by H.M. Heggestad. Analytic results with the simulator and the steady-state analysis program indicated that the new routing algorithms provided reduced point-to-point blocking probabilities after damage without adding extra trunking. Best performance was obtained with adaptive mixed-media routing and precedence flooding techniques. Guided preemption preempted fewer low-precedence calls than blind preemption as used in AUTOVON to complete the same number of high-precedence calls.

A method and system for routing frames in a multi-ring local area network

Abstract: The architecture provides a frame format and procedure for routing messages through a single ring or multi-ring communication system. Stations associated with the exchange of messages are located on the single ring or on different rings of the multi-ring communication system. The rings are connected by bridges to form a physical local area network. The frame format includes a plurality of control bits positioned within a Routing Information (RI) field, a frame control field and a frame status field. Messages are generated and structured in accordance with the frame format. A group of the control bits, in each message, is set with initial values according to the message type. Thus, different messages are characterized by a different sequence of control bit settings. A routing algorithm analyzes the message and depending on the status of the control bits, the message is processed and ultimately switched to its proper destination.

Fault location in distributed control interconnection networks

Abstract: One class of networks suitable for use in parallel processing systems is the multistage cube network. Unfor- tunately, the cube network is not fault tolerant and any single failure within the network can prevent some source- destination communications. Cube networks with "extra" stages can be constructed that permit faults to be bypassed — providing the exact location of the fault is known. This paper focuses on fault location procedures suitable for use in net- works that employ distributed routing control through the use of routing tags and message transmission protocols. Faults occurring in the data lines can corrupt message routing tags transmitted over them and thereby cause misrouting of mes- sages. Protocol lines (used in handshaking between network sources and destinations), if faulty, can prevent a message path from being established or can cause the path to "lock- up" once transmission of data has begun. These faults have more pronounced effects on the network performance than faults previously considered for centralized routing control systems. The fault location procedures presented form a logi- cal superset to those of the centralized control systems (where message routing is dictated by the actions of a global control unit) and can be adapted for use in both circuit and packet switching networks.

Adaptive routing in radio communication networks

Abstract: After a brief review of the field of routing algorithms for communication networks this paper focuses on adaptive routing for radio networks of mobile nodes. Two algorithms are proposed and their performance is evaluated and compared to that of flooding.

Computation of Total Service Time in a Packet Switched, Store-and-Forward Computer Communication Network

Abstract: Packet switched computer communication networks consist of switching centres connected by communication channels which allow the storing and forwarding of message packets from source node to destination node. The routing procedure generally attempts to minimize the average time a message spends in the network.In the networks discussed in this paper, we don't make usual independence assumption and permit general arrival distribution and forwarding as-soon-as available policy. The queueing theory approximations are not valid in this situation and therefore another fast approximate technique to calculate total service time and to obtain routing solutions is suggested.First, two-are three-node networks are considered and the discussion is then generalized for calculating the service time for shipment of a given number of packets over a path between a fixed source and destination node. Lastly, a method for evolving an optimal strategy for routing the packets over a set of disjoint paths so as to minimize the s...