Showing papers on "Routing (electronic design automation) published in 2001"

Tapestry: An Infrastructure for Fault-tolerant Wide-area Location and Routing

Abstract: In today’s chaotic network, data and services are mobile and replicated widely for availability, durability, and locality. Components within this infrastructure interact in rich and complex ways, greatly stressing traditional approaches to name service and routing. This paper explores an alternative to traditional approaches called Tapestry. Tapestry is an overlay location and routing infrastructure that provides location-independent routing of messages directly to the closest copy of an object or service using only point-to-point links and without centralized resources. The routing and directory information within this infrastructure is purely soft state and easily repaired. Tapestry is self-administering, faulttolerant, and resilient under load. This paper presents the architecture and algorithms of Tapestry and explores their advantages through a number of experiments.

A unified tabu search heuristic for vehicle routing problems with time windows

Abstract: This paper presents a unified tabu search heuristic for the vehicle routing problem with time windows and for two important generalizations: the periodic and the multi-depot vehicle routing problems with time windows. The major benefits of the approach are its speed, simplicity and flexibility. The performance of the heuristic is assessed by comparing it to alternative methods on benchmark instances of the vehicle routing problem with time windows. Computational experiments are also reported on new randomly generated instances for each of the two generalizations.

Tapestry: An Infrastructure for Fault-tolerant Wide-area Location and

Abstract: In today''s chaotic network, data and services are mobile and replicated widely for availability, durability, and locality. Components within this infrastructure interact in rich and complex ways, greatly stressing traditional approaches to name service and routing. This paper explores an alternative to traditional approaches called Tapestry. Tapestry is an overlay location and routing infrastructure that provides location-independent routing of messages directly to the closest copy of an object or service using only point-to-point links and without centralized resources. The routing and directory information within this infrastructure is purely soft state and easily repaired. Tapestry is self-administering, fault-tolerant, and resilient under load. This paper presents the architecture and algorithms of Tapestry and explores their advantages through a number of experiments.

On calculating power-aware connected dominating sets for efficient routing in ad hoc wireless networks

Abstract: Efficient routing among a set of mobile hosts (also called nodes) is one of the most important functions in ad hoc wireless networks. Routing based on a connected dominating set is a promising approach, where the searching space for a route is reduced to nodes in the set. A set is dominating if all the nodes in the system are either in the set or neighbors of nodes in the set. J. Wu and H. Li (1999) proposed a simple and efficient distributed algorithm for calculating connected dominating set in ad hoc wireless networks, where connections of nodes are determined by geographical distances of nodes. In general, nodes in the connected dominating set consume more energy in order to handle various bypass traffics than nodes outside the set. To prolong the life span of each node, and hence, the network by balancing the energy consumption in the network, nodes should be alternated in being chosen to form a connected dominating set. In this paper, we propose a method of calculating power-aware connected dominating set. Our simulation results show that the proposed approach outperforms several existing approaches in terms of life span of the network.

Wireless packet switched communication systems and networks using adaptively steered antenna arrays

Abstract: Methods, apparatuses and systems are provided for use in a wireless routing network. One apparatus, for example, includes an adaptive antenna that is configurable to receive a transmission signal from a transmitter and in response transmit corresponding outgoing multi-beam electromagnetic signals exhibiting a plurality of selectively placed transmission peaks and transmission nulls within a far field region of a coverage area. The adaptive antenna may also be configured to selectively receive at least one incoming electromagnetic signal directed through the coverage area. The adaptive antenna includes at least one antenna array and logic. The antenna array has a plurality of antenna elements. The logic is operatively coupled to the antenna array and configured to selectively control the placement of the transmission peaks and transmission nulls within the outgoing multi-beam electromagnetic signals. The logic may also be configured to selectively control the reception of at least one incoming electromagnetic signal. The logic is configured to be responsive to routing information. Such routing information may be dynamically maintained in one or more routing tables.

Towards an analysis of onion routing security

Abstract: This paper presents a security analysis of Onion Routing, an application independent infrastructure for traffic-analysis-resistant and anonymous Internet connections. It also includes an overview of the current system design, definitions of security goals and new adversary models.

Lagrange relaxation based method for the QoS routing problem

Abstract: In this paper a practically efficient QoS routing method is presented, which provides a solution to the delay constrained least cost routing problem. The algorithm uses the concept of aggregated costs and provides an efficient method to find the optimal multiplier based on Lagrange relaxation. This method is proven to be polynomial and it is also efficient in practice. The benefit of this method is that it also gives a lower bound on the theoretical optimal solution along with the result. The difference between the lower bound and the cost of the found path is very small proving the good quality of the result. Moreover, by further relaxing the optimality of paths, an easy way is provided to control the trade-off between the running time of the algorithm and the quality of the found paths. We present a comprehensive numerical evaluation of the algorithm, by comparing it to a wide range of QoS routing algorithms proposed in the literature. It is shown that the performance of the proposed polynomial time algorithm is close to the optimal solution computed by an exponential algorithm.

Wdm Optical Networks: Concepts, Design and Algorithms

Abstract: (NOTE: Each chapter begins with an Introduction and concludes with Problems.) Preface. 1. WDM Technology and Issues in WDM Optical Networks. Optical Networks. Wavelength Division Multiplexing. WDM Optical Networking Evolution. Enabling Technologies for WDM Optical Networks. WDM Optical Network Architectures. Issues in Wavelength Routed Networks. Next-Generation Optical Internet Networks. Book Overview. 2. Wavelength Routing Algorithms. Classification of RWA Algorithms. RWA Algorithms. Fairness and Admission Control. Distributed Control Protocols. Permutation Routing and Wavelength Requirements. Summary. 3. Wavelength-Convertible Networks. Need for Wavelength Converters. Wavelength-Convertible Switch Architectures. Routing in Convertible Networks. Performance Evaluation of Convertible Networks. Networks with Sparse Wavelength Conversion. Converter Placement Problem. Converter Allocation Problem. Summary. 4. Wavelength Rerouting Algorithms. Benefits of Wavelength Rerouting. Issues in Wavelength Rerouting. Lightpath Migration. Rerouting Schemes. Algorithm AG. Algorithm MWPG. Rerouting in WDM Networks with Sparse Wavelength Conversion. Rerouting in Multifiber Networks. Rerouting in Multifiber Unidirectional Ring Networks. Summary. 5. Virtual Topology Design. Virtual Topology Design Problem. Virtual Topology Design Subproblems. Virtual Topology Problem Formulation. Virtual Topology Design Heuristics. Regular Virtual Topology Design. Predetermined Virtual Topology and Lightpath Routes. Predetermined Virtual Topology. Design of Multifiber Networks. Summary. 6. Virtual Topology Reconfiguration. Need for Virtual Topology Reconfiguration. Reconfiguration Due to Traffic Changes. Reconfiguration for Fault Restoration. Summary. 7. Network Survivability and Provisioning. Failures and Recovery. Restoration Schemes. Multiplexing Techniques. Provisioning Restorable Multifiber Networks. Provisioning Restorable Single-Fiber Networks. Backup Multiplexing-Based Routing. Primary-Backup Multiplexing-Based Routing. Distributed Control Protocols. Survivability in WDM Ring Networks. Summary. 8. Optical Multicast Routing. Multicast Routing Problem. Node Architectures. Multicast Tree Generation. Source-Based Tree Generation. Steiner-Based Tree Generation. Virtual Source-Based Trees. Summary. 9. Next-Generation Optical Internet Networks. Optical Circuit Switching. Optical Burst Switching. Optical Packet Switching. MPLS in WDM Networks. Summary. References. Appendices. AWEB RESOURCES LIST. BATM Technology. CSONET Technology. DMPLS Framework. Acronyms. Index.

Method for design optimization using logical and physical information

Abstract: A method for design optimization using logical and physical information is provided. In one embodiment, a method for design optimization using logical and physical information, includes receiving a behavioral description of an integrated circuit or a portion of an integrated circuit, optimizing placement of circuit elements in accordance with a first cost function, and optimizing logic of the circuit elements in accordance with a second cost function, in which the optimizing placement of the circuit elements and the optimizing logic of the circuit elements are performed concurrently. The method can further include optimizing routing in accordance with a third cost function, in which the optimizing routing, the optimizing placement of the circuit elements, and the optimizing logic of the circuit elements are performed concurrently.

Dynamic lightpath establishment in wavelength routed WDM networks

Abstract: In wavelength-routed WDM networks, a control mechanism is required to set up and take down all-optical connections. Upon the arrival of a connection request, this mechanism must be able to select a route, assign a wavelength to the connection, and configure the appropriate optical switches in the network. The mechanism must also be able to provide updates to reflect which wavelengths are currently being used on each link so that nodes may make informed routing decisions. In this work, we review control mechanisms proposed in the literature. We also investigate and compare two different distributed control mechanisms for establishing all-optical connections in a wavelength-routed WDM network: an approach based on link-state routing, and one based on distance-vector routing.

Methods and apparatus for displaying a travel route and/or generating a list of places of interest located near the travel route

Abstract: An automated travel planning apparatus includes three separate databases, including a map database for storing bit-mapped images covering numerous geographic regions, a routing database for storing node, link, and shape data for roads geographically located within the geographic regions and for storing place data indicating the geographic location of places such as towns and cities, and a places of interest database containing the geographic locations of numerous places of interest. A processor within the automated travel planning apparatus may be divided into several functional components, including a map selection component, a routing component, and a place selection component. In response to user input at the user interface, the map selection component chooses a bit-mapped image from the map database for display on the display monitor. After a user selects, via the user interface, a departure point and a destination point, the routing component employs the routing database to generate and display a route between the selected departure and destination points. If the user requests a list of places near the displayed route, the place selection component employs the places of interest database to generate and display a list of places of interest which are within a predetermined distance of the generated route.

Layout and routing methods for warehouses

Abstract: textLayout and Routing Methods for Warehouses discusses aspects of order picking in warehouses Order picking is the process by which products are retrieved from storage to meet customer demand Various new routing methods are introduced to determine efficient sequences in which products have to be retrieved from storage Furthermore, a new method is given to determine a layout for the order picking area The objective is to minimize the average distance traveled per route by the order pickers

Design of logical topologies: a linear formulation for wavelength-routed optical networks with no wavelength changers

Abstract: We consider the problem of constructing logical topologies over a wavelength-routed optical network with no wavelength changers. We present a general linear formulation which considers routing traffic demands, and routing and assigning wavelengths to lightpaths, as a combined optimization problem. The formulation also takes into account the maximum number of hops a lightpath is permitted to take, multiple logical links in the logical topology, multiple physical links in the physical topology, and symmetry/asymmetry restrictions in designing logical topologies. The objective is to minimize congestion. We show by examples how equality and inequality logical degree constraints have a bearing on congestion. We prove that, under certain conditions, having equality degree constraints with multiple edges allowed in the design of logical topologies does not affect congestion. This helps in reducing the dimensionality of the search space and hence speeds up the search for an optimal solution of the linear formulation. We solve the linear formulation for small examples and show the tradeoff between congestion, number of wavelengths available and the maximum number of hops a lightpath is allowed to take. For large networks, we solve the linear formulation by relaxing the integer constraints. We develop topology design algorithms for large networks based on rounding the solutions obtained by solving the relaxed problem. Since the whole problem is linearizable, the solution obtained by relaxation of the integer constraints yields a lower bound on congestion. This is useful in comparing the efficiency of our heuristic algorithms. Following Bienstock and Gunluk (1995), we introduce a cutting plane which helps in obtaining better lower bounds on congestion and also enables us to reduce the previously obtained upper bounds on congestion.

Constraint-based watermarking techniques for design IP protection

Abstract: Digital system designs are the product of valuable effort and know-how. Their embodiments, from software and hardware description language program down to device-level netlist and mask data, represent carefully guarded intellectual property (IP). Hence, design methodologies based on IP reuse require new mechanisms to protect the rights of IP producers and owners. This paper establishes principles of watermarking-based IP protection, where a watermark is a mechanism for identification that is: (1) nearly invisible to human and machine inspection; (2) difficult to remove; and (3) permanently embedded as an integral part of the design. Watermarking addresses IP protection by tracing unauthorized reuse and making untraceable unauthorized reuse as difficult as recreating given pieces of IP from scratch. We survey related work in cryptography and design methodology, then develop desiderata, metrics, and concrete protocols for constraint-based watermarking at various stages of the very large scale integration (VLSI) design process. In particular, we propose a new preprocessing approach that embeds watermarks as constraints into the input of a black-box design tool and a new postprocessing approach that embeds watermarks as constraints into the output of a black-box design tool. To demonstrate that our protocols can be transparently integrated into existing design flows, we use a testbed of commercial tools for VLSI physical design and embed watermarks into real-world industrial designs. We show that the implementation overhead is low-both in terms of central processing unit time and such standard physical design metrics as wirelength, layout area, number of vias, and routing congestion. We empirically show that the placement and routing applications considered in our methods achieve strong proofs of authorship and are resistant to tampering and do not adversely influence timing.

A Rollout Policy for the Vehicle Routing Problem with Stochastic Demands

Abstract: The paper considers the single vehicle routing problem with stochastic demands. While most of the literature has studied the a priori solution approach, this work focuses on computing a reoptimization-type routing policy. This is obtained by sequentially improving a given a priori solution by means of a rollout algorithm. The resulting rollout policy appears to be the first computationally tractable algorithm for approximately solving the problem under the reoptimization approach. After describing the solution strategy and providing properties of the rollout policy, the policy behavior is analyzed by conducting a computational investigation. Depending on the quality of the initial solution, the rollout policy obtains 1% to 4% average improvements on the a priori approach with a reasonable computational effort.

A design space evaluation of grid processor architectures

Abstract: In this paper, we survey the design space of a new class of architectures called Grid Processor Architectures (GPAs). These architectures are designed to scale with technology, allowing faster clock rates than conventional architectures while providing superior instruction-level parallelism on traditional workloads and high performance across a range of application classes. A GPA consists of an array of ALUs, each with limited control, connected by a thin operand network. Programs are executed by mapping blocks of statically scheduled instructions to the ALU array and executing them dynamically in dataflow order. This organization enables the critical paths of instruction blocks to be executed on chains of ALUs without transmitting temporary values back to the register file, avoiding most of the large, unscalable structures that limit the scalability of conventional architectures. Finally, we present simulation results of a preliminary design, the GPA-1. With a half-cycle routing delay, we obtain performance roughly equal to an ideal 8-way, 512-entry window superscalar core. With no inter-ALU delay, perfect memory, and perfect branch prediction, the IPC of the GPA-1 is more than twice that of the ideal superscalar core, achieving an average of 11 IPC across nine SPEC CPU2000 and Mediabench benchmarks.

Stability issues in OSPF routing

Abstract: We study the stability of the OSPF protocol under steady state and perturbed conditions. We look at three indicators of stability, namely, (a) network convergence times, (b) routing load on processors, and (c) the number of route flaps. We study these statistics under three different scenarios: (a) on networks that deploy OSPF with TE extensions, (b) on networks that use subsecond HELLO timers, and (c) on networks that use alternative strategies for refreshing link-state information. Our results are based on a very detailed simulation of a real ISP network with 292 nodes and 765 links.

Fast updating algorithms for TCAM

Abstract: One popular hardware device for performing fast routing lookups and packet classification is a ternary content-addressable memory (TCAM). This paper proposes two algorithms to manage the TCAM such that incremental update times remain small in the worst case.

Blocking and Routing Discrete Solitons in Two-Dimensional Networks of Nonlinear Waveguide Arrays

Abstract: It is shown that discrete solitons can be navigated in two-dimensional networks of nonlinear waveguide arrays. This can be accomplished via vector interactions between two classes of discrete solitons: signals and blockers. Discrete solitons in such two-dimensional networks can exhibit a rich variety of functional operations, e.g., blocking, routing, logic functions, and time gating.

System and method to internetwork wireless telecommunication networks

Abstract: One aspect of the invention is a method for wireless call processing. The method includes downloading at least one function-specific logic control program into each of a plurality of generic logic control state machines and receiving a message at a wireless protocol-specific codec, parsing the message, and routing the message to a first logic control state machine associated with the protocol-specific codec. The method also includes executing the function-specific logic control program of a first logic control state machine and generating a call event and routing the call event to an event codec. The method also includes executing the function-specific logic control program of a second logic control state machine and processing the call event. In a particular embodiment, the method also includes allocating an RF channel that may be used for the call event without seizing the RF channel. In another embodiment, the method also includes accessing a database that includes routing and verification information related to the call event, and routing the call event in response to the information.

Method and apparatus for a network independent short message delivery system

Abstract: Techniques are described for facilitating communication among a plurality of different telecommunications system. Communications from a sending network are forwarded to a server that places the communications in a format acceptable to a second receiving network. The server maps an incoming message into any one or more of a variety of formats in accordance with a format acceptable by a receiving network. These communications may include, for example, short messages service (SMS) messages in which the sending and receiving telecommunications systems each have different routing information, such as different electronic addressing formats.

Hierarchical placement and network design problems

Abstract: Gives constant approximations for a number of layered network design problems. We begin by modeling hierarchical caching, where the caches are placed in layers and each layer satisfies a fixed percentage of the demand (bounded miss rates). We present a constant approximation to the minimum total cost of placing the caches and to the routing demand through the layers. We extend this model to cover more general layered caching scenarios, giving a constant combinatorial approximation to the well-studied multi-level facility location problem. We consider a facility location variant, the load-balanced facility location problem, in which every demand is served by a unique facility and each open facility must serve at least a certain amount of demand. By combining load-balanced facility location with our results on hierarchical caching, we give a constant approximation for the access network design problem.

Optimal Feeder Routing in Distribution System Planning Using Dynamic Programming Technique and GIS Facilities

Abstract: Optimal feeder routing is an important part of the general optimal distribution network planning. This paper proposes a new algorithm for the optimal feeder routing problem using the dynamic programming technique and geographical information systems (GIS) facilities. All practical issues, such as cost parameters (investments, line losses, reliability) and technical constraints (voltage drop and thermal limits), as well as physical routing constraints (obstacles, high-cost passages, existing line sections) are taken into consideration. The algorithm developed is validated comparing its results for a simplified study case, with those obtained by an established solver. The effectiveness of the algorithm is further illustrated for a "real-world" study case.

Estimating routing congestion using probabilistic analysis

Abstract: Design routability is a major concern in the ASIC design flow, particularly with todays increasingly aggressive process technology nodes. Increased die areas, cell densities, routing layers, and net count all contribute to complex interconnect requirements, which can significantly deteriorate performance, and sometimes lead to unroutable solutions. Congestion analysis and optimization must be performed early in the design cycle to improve routability. This paper presents a congestion estimation algorithm for a placed netlist. We propose a net-based stochastic model for computing expected horizontal and vertical track usage, which considers routing blockages. The main advantages of this algorithm are accuracy and fast runtime. We show that the congestion estimated by this algorithm correlates well with post-route congestion, and show experimental results of subsequent congestion optimization based this algorithm.

Interconnection network for a field programmable gate array

Abstract: An interconnection network architecture which provides an interconnection network which is especially useful for FPGAs is described. Based upon Benes networks, the resulting network interconnect is rearrangeable so that routing between logic cell terminals is guaranteed. Upper limits on time delays for the network interconnect are defined and pipelining for high speed operation is easily implemented. The described network interconnect offers flexibility so that many design options are presented to best suit the desired application.

Method and apparatus for an attribute oriented routing update

Abstract: A computer implemented method and apparatus for an attribute-oriented routing update is described. The method comprises selecting an updated set of attributes in a routing table before selecting a set of updated destinations associated with the selected set of attributes, wherein the attributes are stored in an attribute table as a portion of the routing table and the attributes do not include the conventional network prefixes. An update message that includes the set of updated destinations for the set of attributes is then generated. The method is also extended to extraction of unreachable destinations by using a dummy attribute in the routing table, wherein the dummy attribute is selected first, followed by extracting the unreachable destinations.

RC delay metrics for performance optimization

Abstract: For performance optimization tasks such as floorplanning, placement, buffer insertion, wire sizing, and global routing, the Elmore resistance-capacitance (RC) delay metric remains popular due to its simple closed form expression, fast computation speed, and fidelity with respect to simulation. More accurate delay computation methods are typically central processing unit intensive and/or difficult to implement. To bridge this gap between accuracy and efficiency/simplicity, we propose two new RC delay metrics called delay via two moments (D2M) and effective capacitance metric (ECM), which are virtually as simple and fast as the Elmore metric, but more accurate. D2M uses two moments of the impulse response in a simple formula that has high accuracy at the far end of RC lines. ECM captures resistive shielding effects by modeling the downstream capacitance by an "effective capacitance." In contrast, the Elmore metric models this as a lumped capacitance, thereby ignoring resistive shielding. Although not as accurate as D2M, ECM yields consistent performance and may be well-suited to optimization due to its Elmore-like recursive construction.