Showing papers on "Routing table published in 1987"
TL;DR: In this article, a deadlock-free routing algorithm for arbitrary interconnection networks using the concept of virtual channels is presented, where the necessary and sufficient condition for deadlock free routing is the absence of cycles in a channel dependency graph.
Abstract: A deadlock-free routing algorithm can be generated for arbitrary interconnection networks using the concept of virtual channels. A necessary and sufficient condition for deadlock-free routing is the absence of cycles in a channel dependency graph. Given an arbitrary network and a routing function, the cycles of the channel dependency graph can be removed by splitting physical channels into groups of virtual channels. This method is used to develop deadlock-free routing algorithms for k-ary n-cubes, for cube-connected cycles, and for shuffle-exchange networks.
2,110 citations
TL;DR: Several distributed routing rules are investigated that take advantage of the regular structure of the Manhattan Street Network, and two procedures are described that allow the network to adapt to node or link failures.
Abstract: The Manhattan Street Network is a regular, two-connected network, designed for packet communications in a local or metropolitan area. It operates as a slotted system, similar to conventional loop networks. Unlike loop networks, routing decisions must be made at every node in this network. In this paper, several distributed routing rules are investigated that take advantage of the regular structure of the network. In an operational network, irregularities occur in the structure because of the addressing mechanisms, adding single nodes, and failures. A fractional addressing scheme is described that makes it possible to add new rows or columns to the network without changing the addresses of existing nodes. A technique is described for adding one node at a time to the network, while changing only two existing links. Finally, two procedures are described that allow the network to adapt to node or link failures. The effect that irregularities have on routing mechanisms designed for a regular structure is investigated.
378 citations
TL;DR: General bounds are derived which show that de Bruijn networks are asymptotically optimal and efficient techniques for building large networks with small forwarding indexes out of given component networks are presented and analyzed.
Abstract: A network is defined as an undirected graph and a routing which consists of a collection of simple paths connecting every pair of vertices in the graph. The forwarding index of a network is the maximum number of paths passing through any vertex in the graph. Thus it corresponds to the maximum amount of forwarding done by any node in a communication network with a fixed routing. For a given number of vertices, each having a given degree constraint, we consider the problem of finding networks that minimize the forwarding index. Forwarding indexes are calculated' for cube networks and generalized de Bruijn networks. General bounds are derived which show that de Bruijn networks are asymptotically optimal. Finally, efficient techniques for building large networks with small forwarding indexes out of given component networks are presented and analyzed.
107 citations
TL;DR: This paper presents a new routing technique that can be applied for general two-layer detailed routing problems, including switchboxes, channels, and partially routed areas, and has performed as well as or better than existing algorithms.
Abstract: For the macrocell design style and for routing problems in which the routing regions are irregular, two-dimensional routers are often necessary. In this paper, a new routing technique that can be applied for general two-layer detailed routing problems, including switchboxes, channels, and partially routed areas, is presented. The routing regions that can be handled are very general: the boundaries can be described by any rectilinear edges, the pins can be on or inside the boundaries of the region, and the obstructions can be of any shape and size. The technique is based on an algorithm that routes the nets in the routing region incrementally and intelligently, and allows modifications and rip-up of nets when an existing shortest path is "far" from optimal or when no path exists. The modification steps (also called weak modification) relocate some segments of nets already routed to find a shorter path or to make room for a blocked net. The rip-up and reroute steps (called strong modifiction) remove segments of nets already routed to make room for a blocked connection; these steps are invoked only if weak modification fails. The algorithm has been rigorously proven to complete in finite time and its complexity has been analyzed. The algorithm has been implemented in the "C" programming language. Many test cases have been run, and on all the examples known in the literature the router has performed as well as or better than existing algorithms. In particular, Burstein's difficult switchbox example has been routed using one less column than the original data. In addition, the router has routed difficult channels such as Deutsch's in density and has performed better than or as well as YACR-II on all the channels available to us.
103 citations
Patent•
24 Aug 1987
TL;DR: In this paper, the window manager may modify the routing table and all keycodes remaining in the buffer are routed to their associated processes as determined by the modified routing table, unless otherwise indicated, a keycode is routed to the active process.
Abstract: A computer system in which multiple processes may run concurrently includes a window manager for displaying windows associated with different processes. One of the processes represented by a window may be designated as active. Keystrokes are translated by a keyboard driver to events represented by keycodes. The keycodes are routed to processes with which they are associated by reference to a routing table. Unless otherwise indicated, a keycode is routed to the active process. Where a keycode is associated with and transferred to the window manager, subsequent keycodes are stored in a typeahead buffer. The window manager may modify the routing table. After completion of the window manager operation, all keycodes remaining in the buffer are routed to their associated processes as determined by the modified routing table.
70 citations
TL;DR: Given a network with a predefined routing, the effects of faulty components on the routing is studied and the number of routes along which a message must travel between any two non-faulty nodes is analyzed.
Abstract: We model a communication network as a graph in which a processor is a node and a communication link is an edge. A routing for such a network is a fixed path, or route, between each pair of nodes. Given a network with a predefined routing, we study the effects of faulty components on the routing. Of particular interest is the number of routes along which a message must travel between any two non-faulty nodes. This problem is analyzed for specific families of graphs and for classes of routings. We also give some bounds for general versions of the problem. Finally, we conclude with one of the most important contributions of this paper, a list of interesting and apparently difficult open problems.
62 citations
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TL;DR: A permeation routing algorithm is proposed which decides the detailed routes on a new layout model and attains a higher density by using the expanded routing region as well as the conventional one simultaneously.
Abstract: A permeation routing algorithm is proposed which decides the detailed routes on a new layout model. The permeation router attains a higher density by using the expanded routing region as well as the conventional one simultaneously. This routing algorithm consists of two phases. One is to partition the trunk set into three subsets corresponding to the trunks to be routed in the channel on the lower transistor row, upper transistor row, or between transistor rows. The other is to route these channels by using the one-layer channel assignment method as well as the conventional one. The experiments show that the routing results are practical and that the processing time is proportional to the number of trunks to the power of 1.4.
50 citations
Patent•
27 Apr 1987
TL;DR: A message packet router as mentioned in this paper performs the functions of determining if a message packet is addressed to circuitry associated with the router, routing message packets to their distination if possible and storing message packets that cannot be routed on because of circuit conflicts.
Abstract: A message packet router is described that performs the functions of determining if a message packet is addressed to circuitry associated with the router, of routing message packets to their distination if possible and of storing message packets that cannot be routed on because of circuit conflicts. The router also provides additional functions of merging message packets addressed to the same destination, of saving the state of the router at each significant point in the message routing cycle, and of running the entire routing cycle backwards. This later feature makes it possible to broadcast message packets selectively to certain processors in the array.
48 citations
TL;DR: The core of the solution is an algorithm for a generalized version of the token distribution problem that has direct applications to the solution of the load balancing problem in distributed systems.
39 citations
01 Oct 1987
TL;DR: This work presents an approach to channel routing with compaction in which channel compaction is adaptable to several routing criteria priorities, and shows how overall channel routing performance can be improved by taking advantage of this versatility inChannel compaction.
Abstract: A channel router which is to be effective for general-purpose automatic routing must be able to use different sets of routing criteria priorities, in a controllable manner. We present an approach to channel routing with compaction in which channel compaction is adaptable to several routing criteria priorities. We show how overall channel routing performance can be improved by taking advantage of this versatility in channel compaction. We indicate some routing capabilities which cannot be effectively achieved by simply post-processing the output of a traditional gridded channel router. Our solution to this problem is outlined and some results obtained from our router are compared with those of other published channel routers.
36 citations
01 Oct 1987
TL;DR: This paper describes an experiment in which parallel routing is performed on a medium grained hypercube parallel processor having 64 processing elements and was able to route 95 % of the wires using a standard benchmark.
Abstract: This paper describes an experiment in which parallel routing is performed on a medium grained hypercube parallel processor having 64 processing elements. Each node is a complete 32-bit computer with 128 K-bytes of memory and is connected to the other nodes via a direct hypercube interconnection network. A new parallel routing algorithm was developed to exploit this parallel structure. It is a three step algorithm consisting of a global routing step, a boundary crossing placement step, and a detailed routing step. All steps can be performed in parallel. When applied to a standard benchmark it was able to route 95 % of the wires. The algorithm was also executed on a large mainframe computer using the same benchmark. The execution time was compared to that for the hypercube. The hypercube was about three times as fast.
01 Dec 1987
Patent•
03 Aug 1987
TL;DR: An adaptive, tariff dependent traffic routing system, which controls routing of traffic and performs management of network resources in multi-node telecommu-nication networks, where the cost for a communication depends on the type of service provided and on the dis-tance between the originating node and the destination as discussed by the authors.
Abstract: An adaptive, tariff dependent traffic routing system, which controls routing of traffic and performs management of network resources in multi-node telecommunication networks, where the cost for a communication depends on the type of service provided and on the distance between the originating node and the destination. Each node can originate traffic, receive and/or transit traffic over inter-node trunks. The system is realized by means of a central computer, which has connections to the SPC nodes of the network over two-way data links. The computer has access to data stored in the computer's memory, containing the actual distance- and service sensitive tariffs applied in the network. By frequent scanning of the network, the computer has a global view of the actual out-of-service and traffic load status in the nodes and in the different trunk groups. Based on the tariffs and on the global network status view the system determines the policy for routing traffic in the network, such that the revenue is maximized. When determining the routing decisions, the out-of-service and overloaded network equipment is automatically by-passed. Similarly, traffic to out-of-service, overloaded or hard-to-reach destinations is not allowed to enter the network. The same applies to traffic destined to access-restricted nodes. The routing policy is transmitted to the SPC nodes in terms of routing instruc tions, specific for each originating node and each destination as well as specific for each type of a service. Since new instructions are issued after each network scanning, these will vary with the actual traffic and out-of-service situation in the network. In this way an adaptive, revenue maximizing traffic routing and network management system is achieved.
01 Oct 1987
TL;DR: A channel router especially designed for routing macro cells that routes variable-width pins with wires of any width and handles non-rectangular channels with highly irregular heights, and it also handles cyclic vertical constraints.
Abstract: In this paper, we present a channel router especially designed for routing macro cells. The router routes variable-width pins with wires of any width. Although the router uses a routing grid internally, it acts like it is completely gridless to the user. Pins along the top and the bottom edges of the channel can be at any X-location, and the router uses a channel compactor to compact all horizontal segments vertically. The router allows pins to be on either of the two routing layers. If all the power pins are on the same layer, the router routes the whole power bus in one single layer. It handles non-rectangular channels with highly irregular heights, and it also handles cyclic vertical constraints. Finally, the router has been tested with a number of industrial circuits.
01 Dec 1987
TL;DR: This work presents an optimal oblivious randomized algorithm for permutation routing on the MIMD version of Mesh that demonstrates that routing is easier than sorting on theMIMD Mesh.
Abstract: We present an optimal oblivious randomized algorithm for permutation routing on the MIMD version of Mesh. Our routing algorithm routes n2 elements on an n×n Mesh in 2n+O(log n) parallel communication steps with very high probability. Further, the maximum queue length at any node at any time is at the most O(log n) with the same probability. Since 2n is the distance bound for the Mesh, our algorithm is indeed optimal. Generalization of this result to k-dimensional (for any k) Meshes yields an algorithm that runs in time equal to the diameter of the Mesh. A lower bound result of [Schnorr and Shamir 86] states that sorting of n2 elements takes at least 3n steps on an n × n MIMD Mesh (for indexing schemes of practical interest). Thus our algorithm demonstrates that routing is easier than sorting on the MIMD Mesh.
01 Oct 1987
TL;DR: This paper presents an adaptive routing algorithm for a mid-course, space-based SDI architecture that provides rapid recovery from both predictable and unpredictable outages as well as load balancing.
Abstract: This paper presents an adaptive routing algorithm for a mid-course, space-based SDI architecture. The goals include rapid recovery from both predictable and unpredictable outages as well as load balancing. Robust operation is critical. The routing table update algorithm is distributed, and it produces loop-free routes from periodic topology update information. In addition, multiple routes are found from source to destination nodes. This allows load splitting among these routes to achieve more effective load balancing. A heuristic is used to distribute the load among these routes. The basic algorithm also provides a mechanism to provide path diversity for added survivability. Recovery from failures detected locally occurs immediately through the use of alternate routes and an event-driven failure recovery algorithm. Simulation results are presented to demonstrate the algorithm behavior.
Proceedings Article•
01 Jan 1987
01 Oct 1987
TL;DR: A switchbox-type router for custom VLSI module generation as performed by a module planner with a relative pin assignment algorithm for the abstract cells; a global routing penalty function which not only considers previous routes, but also considers gate complexity within the cells; and an efficient optimization algorithm for minimizing the number of tracks running through the module.
Abstract: This paper describes a switchbox-type router for custom VLSI module generation as performed by a module planner. A module is decomposed into abstract cells consisting of global routes and boolean functional specifications. Each abstract cell is given to a cell synthesizer which generates the circuit layout and through-the-cell routing. Abstract routing for a module planner is in some sense similar to switchbox routing to the degree that all of the routes are generated internally within a rectangular boundary (routes are coming from four sides). The principle difference with respect to standard switchbox routing is at the geometric level, where a cell synthesizer generates the routing conduction layers along with circuit devices for each abstract cell within this rectangular region. The aspects of this paper which are thought to be novel contributions are 1) a relative pin assignment algorithm for the abstract cells; 2) a global routing penalty function which not only considers previous routes, but also considers gate complexity within the cells; 3) an efficient optimization algorithm for minimizing the number of tracks running through the module.
01 Aug 1987
TL;DR: The Current BIAS™ routing architecture incorporates improvements in the original algorithm which significantly reduce the recovery time from failures of nodes or links and is virtually loop-free, even during recovery from those failures.
Abstract: The routing function used for Burroughs Network Architecture (BNA) to determine the best routes for traffic through the network is known as the Burroughs Integrated Adaptive Routing System, or BIAS™1Based on the algorithm devised for the MERIT Computer Network [3], BIAS™ is a decentralized, deterministic system which adapts to changes in network topology automatically. The Current BIAS™ routing architecture incorporates improvements [1] in the original algorithm which significantly reduce the recovery time from failures of nodes or links and is virtually loop-free, even during recovery from those failures.BIAS™ automatically re-determines the best routes for traffic throughout the network in response to the following changes to the network topology: a node (an end system or intermediate system) is added to the network;a node is removed from the network;the cost of transiting a node is changed;a logical link (LAN, leased or switched circuit, X.25 virtual circuit) is added to the network;a link is removed from the network; and/orthe cost of transiting a link is changed.
Patent•
02 Feb 1987
TL;DR: In this paper, a buffer state control part grasps the state of a buffer shown on buffer state table 202 and gives the priority to the extracted request to write this result to a carrying request table 206.
Abstract: PURPOSE:To improve the overall working efficiency of an assembly station by knowing the dangerousness for production of a no-operation state at each assembly station from the number of pallets on a buffer. CONSTITUTION:A buffer state control part 201 grasps the state of a buffer shown on a buffer state table 202. A carrying request producing part 203 refers to a table 202, a manufacturing process route table 204 and a priority table 205 to extract a carrying request and gives the priority to the extracted request to write this result to a carrying request table 206. The pallet on a buffer 0 has the next destination buffer D and it is checked whether this pellet can be accepted by the buffer D or not. If this acceptance is impossible, no pallet is transferred to the buffer D from the buffer O. If the acceptance is possible, a pair of buffers O and D is used to give reference to the table 205. Thus the corresponding priority is obtained and the buffers O, D and P are written to the table 206. The procedure is through when all product input and output buffers are processed.
01 Oct 1987
TL;DR: A general approach to routing by a scanning window is presented, and an experimental switch-box router based on this approach is described, which uses a quasi-maximal set of segments and a grade function that imitates human intuition.
Abstract: A general approach to routing by a scanning window is presented, and an experimental switch-box router based on this approach is described. This router first grades conductor segments that are candidates to enter the window according to their estimated contributions to routing success, and then uses a quasi-maximal set of segments. A grade function that imitates human intuition is also described.
TL;DR: The line expansion algorithm provided by Heynes was a new kind of routing algorithm that took advantage of both Lee's algorithm and linear expansion algorithms, but it was less efficient in two layer routing situations.
Abstract: The line expansion algorithm provided by Heynes was a new kind of routing algorithm that took advantage of both Lee's algorithm and linear expansion algorithms, and hence was more efficient. However, it was less efficient in two layer routing situations. In this paper, this problem is analysed and several ways of solving it are proposed. Three criteria are provided in the paper, and these are used in the development of a modified line expansion algorithm. The modified algorithm is not only fast but also consumes less memory in two layer routing situations. Based on this algorithm, a Fortran printed circuit board routing system is built that can solve two layer routing problems with up to 2600 connection lines on a microcomputer with 64 kbyte RAM.
01 May 1987
TL;DR: Simulations show that hybrid, weighted routing is preferable to other adaptive routing techniques for both packet switched networks and integrated networks.
Abstract: Repeated studies have shown that a single switching technique, either circuit or packet switching, cannot optimally support a heterogeneous traffic mix composed of voice, video and data. Integrated networks support such heterogeneous traffic by combining circuit and packet switching in a single network. To manage the statistical variations of network traffic, we introduce a new, adaptive routing algorithm called hybrid, weighted routing. Simulations show that hybrid, weighted routing is preferable to other adaptive routing techniques for both packet switched networks and integrated networks.
TL;DR: Results obtained include state probability, blocking probability, delay, and throughput of a finite queue which accepts batch Poisson inputs and receives service from multiple synchronous servers.
Abstract: This paper studies the effect of routing on the behavior of a finite queue which accepts batch Poisson inputs and receives service from multiple synchronous servers. Upon the arrival of a group of customers idle or pseudoidle servers will be considered first in routing decisions. Otherwise routing will be determined randomly in accordance with a preset probability distribution. Results obtained include state probability, blocking probability, delay, and throughput. Validity of analysis has been verified by computer simulations. These results can he used in evaluating the performance of a computer communication network.
01 Jan 1987
TL;DR: The current BIAS™ routing architecture incorporates improvements in the original algorithm which significantly reduce the recovery time from failures of network elements and is virtually loop-free, even during recovery from those failures.
Abstract: The routing function used for Burroughs Network Architecture (BNA) to determine the best routes for traffic through the network is known as the BURROUGHS INTEGRATED ADAPTIVE ROUTING SYSTEM, or BIAS™.Based on the algorithm devised for the MERIT Computer Network [3], BIAS™ is a decentralized, deterministic system which adapts to changes in network topology automatically. The current BIAS™ routing architecture incorporates improvements in the original algorithm [1] which significantly reduce the recovery time from failures of network elements and is virtually loop-free, even during recovery from those failures.BIAS™ automatically responds to the following changes to the network topology:- a node (an end system or intermediate system) is added to the network;- a node is removed from the network;- the cost of transiting a node is changed;- a logical link (LAN, leased or switched circuit, X.25 virtual circuit) is added to the network;- a link is removed from the network; and/or- the cost of transiting a link is changed;and re-determines the best route for all traffic throughout the network.
TL;DR: An algorithm for minimum delay routing in packet-switched networks which is capable of adapting to changes in network input traffic, the addition of new links and nodes, and the failure of existing links and node is developed and illustrated.
AT&T1
TL;DR: The analysis indicates that significant savings in trunk costs can be realized when the hop and path constraints are relaxed from one to three and that network designs based solely on a network average delay constraint may lead to high end-to-end delays for some node pairs.
01 Oct 1987
TL;DR: This paper presents and analyzes a new hierarchical routing algorithm for large networks based on the definition and maintenance of a hierarchical addressing scheme that is an extension of a new distributed routing algorithm first proposed by the author for flat networks.
Abstract: The overhead of an adaptive routing algorithm becomes prohibitive in a network with numerous nodes (in the order of hundreds or more) and a flat organization. In this paper, we present and analyze a new hierarchical routing algorithm for large networks. The algorithm is based on (1) the definition and maintenance of a hierarchical addressing scheme that is in turn based on the names of nodes that are well known in the network or within regions of the network, and (2) an extension of a new distributed routing algorithm first proposed by the author for flat networks.
TL;DR: A new routing control scheme to be used in the packet communication in the computer network or multiprocessor system with a feature in that ping-pong and loop phenomena, which cause traffic congestion, are not produced in principle.
Abstract: The computer network and multiprocessor system have been developed and studied. They are based on a network composed of nodes containing processors, aiming at the improvement of performance by distributed processing as well as the improvement of reliability by resource distribution. To realize high system performance, adequate routing and flow controls are required in the communication of information among nodes. This paper proposes a new routing control scheme to be used in the packet communication in the computer network or multiprocessor system. The scheme is called potential routing, which models the computer network by an electric circuit, and the packet routing from the source node to the destination node is performed to the potential difference between the adjacent nodes. The node potential is determined first by Kirchhoff's law and is modified dynamically according to the traffic situation during the routing procedure, providing an adequate criterion for the routing. The proposed scheme has a feature in that ping-pong and loop phenomena, which cause traffic congestion, are not produced in principle. It was verified by simulation that the transmission delay is reduced when the traffic is high or unbalanced.
Patent•
31 Jul 1987
TL;DR: In this article, the authors propose to preserve in an actual memory a page which is frequently referred in list processing before and after garbage collection by preserving a page in the real memory.
Abstract: PURPOSE:To speed up processing by preserving in an actual memory a page which is frequently referred in list processing before and after garbage collection CONSTITUTION:All routes in a route table 1 are sequentially taken out, and a logic space page address LPA in a GC page frame table 5 is scanned, whereby a logic page including a cell shown by the route is decided to be in the real memory 4 or not at the time of beginning to collect garbage If the page is in the real memory 4, and the reference bit R of the page is set, processing for moving the route is not made, but the route is added to a processing queue matrix 7 If the page is not in the real memory 4, normal moving processing is applied to the route After the processing of all the routes in the route table 1 is completed, all the routes in the next processing queue matrix 7 are taken out and moved When the movement of all active cells 10 ends in such a way, a pageout inhibition bit 8 in a page frame table 6 is cleared