Showing papers on "Routing protocol published in 1985"

WEAVER: A Knowledge-Based Routing Expert

Abstract: In this paper we describe WEAVER, a channel/switch-box knowledge-based routing program. WEAVER considers all the important routing metrics such as 100% routability, minimum routing area, minimum wire length, and minimum number of vias simultaneously. It allows pre-routed nets, and user interaction throughout the entire routing process. It also relaxes unnecessary constraint of assigning different layers to different directions, the constraint imposed by all of the current channel and switch-box routers. WEAVER is a grid-based router that utilizes two interconnection layers and can be easily expanded to route any shape routing area such as 'T' or '+'. Implemented in OPS5, a production system language, WEAVER routinely produces routings requiring less area than routers that focus on a single routing metric.

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.

Double Loop Network Architectures--A Performance Study

Abstract: Single loop networks tend to become unreliable and suffer from poor performance when the number of nodes in the network becomes large. One approach to increasing reliability and improving performance is to use a double loop. In this paper, the performance (using analytical and simulation models) of a class of highly reliable double loop network architectures is presented. The richer topology of double loop networks allows more sophisticated routing algorithms to be used. Several routing algorithms are studied, including: fixed, adaptive to failure, and fully adaptive to failure and traffic load conditions.

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.

Bifurcated routing in computer networks

Abstract: This paper presents a characterization and a survey of multiple path routing in computer networks. It also develops a routing protocol that achieves load sharing and combines the strengths of both virtual circuit and datagram networks.

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.

An architecture for routing in the ISO connectionless internet

Abstract: The ISO Connectionless Internet Protocol provides a uniform network service over many types of subnetworks. The protocol has currently progressed to the status of draft international standard (DIS 8473). Ideally, the Internet protocol allows for a high degree of connectivity in a global packet-switched network. However, much work needs to be done in the area of routing before this becomes possible in practice.

The EISN Testbed for Evaluation of Network Routing and Control Techniques

Abstract: The Experimental Integrated Switched Network (EISN) was set up to develop and experimentally evaluate new routing and control techniques potentially applicable in the Defense Switched Network, focusing on the new routing and preemption algorithms described in the companion paper [1]. Significant achievements in the EISN effort include establishment of a geographically distributed telecommunications testbed, featuring common channel signalling (CCS), multi-media trunking, and off-the-shelf digital switches with programmable out-board Routing/Control Processors (RCPs). Selected new algorithms have been evaluated in the form of actual implementations on the testbed. A preliminary description of the EISN testbed, its components, and its objectives was given at MILCOM '83 [2], along with earlier steady-state analysis results on the new adaptive routing algorithms. This paper focuses primarily on the EISN testbed as it is now implemented. The design philosophy and functional characteristics of the testbed are presented, and a series of routing and control experiments is described, as well as some additional experiments in voice/data integration using the Transmission Control Protocol (TCP) for the data transfers. The routing experiments are aimed at validating the logic and the CCS protocols developed for the new routing and preemption algorithms described in the companion paper.

A path-oriented routing strategy for packet switching networks with end-to-end protocols

Abstract: A path-oriented routing strategy is proposed for packet switching networks with end-to-end internal protocols. It allows switch pairs to communicate over multiple paths (for better network throughput), while maintaining knowledge of user connections at the network's endpoints only. The most significant aspect of this strategy lies in its flow assignment method. A distributed loop-free shortest path algorithm assigns a number to a path at the time it is created and this number remains valid through shortest path changes. Consequently, existing traffic can be maintained on existing paths, while new traffic is assigned to the current shortest paths. Stable multiple path routing is thus achieved without packet disordering. Abnormal conditions such as trunk failure and recovery and trunk congestion are dealt with by tagging routing updates with update causes. Simulation of this routing strategy shows that maximum network throughput (under a certain congestion constraint) can be increased substantially compared to a single path routing strategy.

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.