Showing papers on "Geographic routing published in 1998"

Internet routing instability

Abstract: This paper examines the network interdomain routing information exchanged between backbone service providers at the major US public Internet exchange points. Internet routing instability, or the rapid fluctuation of network reachability information, is an important problem currently facing the Internet engineering community. High levels of network instability can lead to packet loss, increased network latency and time to convergence. At the extreme, high levels of routing instability have led to the loss of internal connectivity in wide-area, national networks. We describe several unexpected trends in routing instability, and examine a number of anomalies and pathologies observed in the exchange of inter-domain routing information. The analysis in this paper is based on data collected from border gateway protocol (BGP) routing messages generated by border routers at five of the Internet core's public exchange points during a nine month period. We show that the volume of these routing updates is several orders of magnitude more than expected and that the majority of this routing information is redundant, or pathological. Furthermore, our analysis reveals several unexpected trends and ill-behaved systematic properties in Internet routing. We finally posit a number of explanations for these anomalies and evaluate their potential impact on the Internet infrastructure.

Adaptive wavelength routing in all-optical networks

Abstract: We consider routing and wavelength assignment in wavelength-routed all-optical networks (WAN) with circuit switching. The conventional approaches to address this issue consider the two aspects of the problem disjointly by first finding a route from a predetermined set of candidate paths and then searching for an appropriate wavelength assignment. We adopt a more general approach in which we consider all paths between a source-destination (s-d) pair and incorporate network state information into the routing decision. This approach performs routing and wavelength assignment jointly and adaptively, and outperforms fixed routing techniques. We present adaptive routing and wavelength assignment algorithms and evaluate their blocking performance. We obtain an analytical technique to compute approximate blocking probabilities for networks employing fixed and alternate routing. The analysis can also accommodate networks with multiple fibers per link. The blocking performance of the proposed adaptive routing algorithms are compared along with their computational complexity.

The performance of query control schemes for the zone routing protocol

Abstract: In this paper, we study the performance of route query control mechanisms for the recently proposed Zone Routing Protocol (ZRP) for ad-hoc networks. The ZRP proactively maintains routing information for a local neighborhood (routing zone), while reactively acquiring routes to destinations beyond the routing zone. This hybrid routing approach has the potential to be more efficient in the generation of control traffic than traditional routing schemes. However, without proper query control techniques, the ZRP can actually produce more traffic than standard flooding protocols.Our proposed query control schemes exploit the structure of the routing zone to provide enhanced detection (Query Detection (QD1/QD2)), termination (Loop-back Termination (LT), Early Termination (ET)) and prevention (Selective Bordercasting (SBC)) of overlapping queries. We demonstrate how certain combinations of these techniques can be applied to single channel or multiple channel ad-hoc networks to improve both the delay and control traffic performance of the ZRP. Our query control mechanisms allow the ZRP to provide routes to all accessible network nodes with only a fraction of the control traffic generated by purely proactive distance vector and purely reactive flooding schemes, and with a response time as low as 10% of a flooding route query delay.

Global state routing: a new routing scheme for ad-hoc wireless networks

Abstract: In an ad-hoc environment with no wired communication infrastructure, it is necessary that mobile hosts operate as routers in order to maintain the information about connectivity. However with the presence of high mobility and low signal/interference ratio (SIR), traditional routing schemes for wired networks are not appropriate, as they either lack the ability to quickly reflect the changing topology, or may cause excessive overhead, which degrades network performance. Considering these restrictions, we propose a new scheme especially designed for routing in an ad-hoc wireless environments. We call this scheme "global state routing" (GSR), where nodes exchange vectors of link states among their neighbors during routing information exchange. Based on the link state vectors, nodes maintain a global knowledge of the network topology and optimize their routing decisions locally. The performance of the algorithm, studied in this paper through a series of simulations, reveals that this scheme provides a better solution than existing approaches in a truly mobile, ad-hoc environment.

Routing and mobility management protocols for ad-hoc networks

Abstract: Two network communication protocols, one for routing and one for mobility management, are presented that are particularly suited for use with ad-hoc networks. The routing protocol is a proactive-reactive hybrid routing protocol that limits the scope of the proactive procedure to the node's local neighborhood. Routing zones are defined for each node that include nodes whose distance from the subject node in hops is at most some predefined number, referred to as the zone radius. Each node is required to know the topology of the network within its routing zone only. The reactive procedure is limited during route discovery to queries of only those nodes located on the periphery of routing zones. In this manner, the queries hop across nodes in distances of zone radius, thus limiting the scope of the reactive procedure. The zone radius is preferably adjustable to accommodate different and differing network topologies and network operational conditions in the most efficient manner. The mobility management protocol relies on some network nodes assuming the mobility management function. In this scheme, each network node is “associated” with one or more mobility management nodes. The mobility management nodes form a virtual network which is embedded within the actual ad-hoc network. Each mobility management node knows the location of all nodes within its zone, and communicates this information to any other mobility management node that requests it.

Mobile agents for adaptive routing

Abstract: This paper introduces AntNet, a new routing algorithm for telecommunication networks. AntNet is an adaptive, distributed, mobile-agents-based algorithm which was inspired by recent work on the ant colony metaphor. We apply AntNet in a datagram network and compare it with both static and adaptive state-of-the-art routing algorithms. We ran experiments for various paradigmatic temporal and spatial traffic distributions. AntNet showed both very good performances and robustness under all the experimental conditions with respect to its competitors.

QoS routing in ad hoc wireless networks

Abstract: The emergence of nomadic applications have generated a lot of interest in wireless network infrastructures which support multimedia services. We propose a bandwidth routing algorithm for multimedia support in a multihop wireless network. This network can be interconnected to wired networks (e.g. ATM or the Internet) or stand alone. Our bandwidth routing includes bandwidth calculation and reservation schemes. Under such a routing algorithm, we can derive a route to satisfy the bandwidth requirement for the QoS constraint. At a source node, the bandwidth information can be used to decide to accept a new call or not immediately. This is specially important to carry out a fast handoff when interconnecting to an ATM backbone infrastructure. It enables an efficient call admission control. The simulation results show that the bandwidth routing algorithm is very useful in extending the ATM virtual circuit service to the wireless network. Different types of QoS traffic can be integrated in such a dynamic radio network with high performance.

A distributed algorithm of delay-bounded multicast routing for multimedia applications in wide area networks

Abstract: Multicast routing is to find a tree which is rooted from a source node and contains all multicast destinations. There are two requirements of multicast routing in many multimedia applications: optimal network cost and bounded delay. The network cost of a tree is defined as the sum of the cost of all links in the tree. The bounded delay of a routing tree refers to the feature that the accumulated delay from the source to any destination along the tree shall not exceed a prespecified bound. This paper presents a distributed heuristic algorithm which generates routing trees having a suboptimal network cost under the delay bound constraint. The proposed algorithm is fully distributed, efficient in terms of the number of messages and convergence time, and flexible in dynamic membership changes. A large amount of simulations have been done to show the network cost of the routing trees generated by our algorithm is similar to, or even better than, other existing algorithms.

Routing area updating in packet radio network

Abstract: The invention relates to a cellular packet radio network and to a method for updating a routing area in a packet radio network. Packet radio support nodes (SGSN) are connected to a digital cellular radio network (BSS), which provides a radio interface for the support nodes for packet-switched data transmission between the support nodes and mobile stations. There is a logical link between a mobile station (MS) and a serving packet radio support node (SGSN). The packet radio network utilizes logical routing areas, each of which comprises one or more cells. Each cell broadcasts information on the routing area to which it belongs. The mobile station sends a routing area update request to the packet radio network when it roams to a new cell which belongs to a different routing area than the old cell. The update request includes the identifiers of the old and new routing area. When the packet radio node detects a routing area update carried out by an unknown mobile station, it initiates the establishment of a logical link by sending a link establishment message (LLC Subm, 21, 21') to the mobile station, the message including the same identifier the mobile station used for itself in the routing area update request. The mobile station initializes the logical link at its own end and sends and acknowledgement to the serving packet radio support node.

Distributed QoS routing with imprecise state information

Abstract: The goal of quality-of-service (QoS) routing is to find a network path which has sufficient resources to satisfy certain constraints on delay, bandwidth and/or other metrics. The network state information maintained at every node is often imprecise in a dynamic environment because of nonnegligible propagation delay of state messages, periodic updates due to overhead concern, and hierarchical state aggregation. The information imprecision makes QoS routing difficult. The traditional shortest-path routing algorithm does not provide satisfactory performance with imprecise state information. We propose a distributed routing scheme, called ticket-based probing, which searches multiple paths in parallel for a satisfactory one. The scheme is designed to work with imprecise state information. It allows the dynamic trade-off between the routing performance and the overhead. The state information of intermediate nodes is collectively used to guide the routing messages along the most appropriate paths in order to maximize the success probability. The proposed algorithm consider not only the QoS requirements but also the cost optimality of the routing path. Extensive simulations show that our algorithm achieve high call-admission ratio and low-cost routing paths with modest overhead. The algorithm can tolerate high degree of information imprecision.

Adaptive Agent-Driven Routing and Load Balancing in Communication Networks

Abstract: This paper presents an unified overview of a new family of distributed algortithms for routing and load balancing in dynamic communication networks. These new algorithms are described as an extension to the classical routing algorithms: they combine the ideas of online asynchronous distance vector routing with adaptive link state routing. Estimates of the current traffic condition and link costs are measured by sending routing agents in the network that mix with the regular information packets and keep track of the costs (e.g. delay) encountered during their journey. The routing tables are then regularly updated based on that information without any central control nor complete knowledge of the network topology. Two new algorithms are proposed here. The first one is based on round trip routing agents that update the routing tables by backtracking their way after having reached the destination. The second one relies on forward agents that update the routing tables directly as they move toward their destination. An efficient co-operative scheme is proposed to deal with asymmetric connections. All these methods are compared on a simulated network with various traffic loads; the robustness of the new algorithms to network changes is proved on various dynamic scenarii.

Distributed quality-of-service routing in high-speed networks based on selective probing

Abstract: We propose an integrated QoS routing framework based on selective probing for high-speed packet-switching networks. The framework is fully distributed and depends only on the local state maintained at every individual node. By using controlled diffusion computations, the framework captures the common messaging and computational structure of distributed QoS routing, and allows an efficient implementation due to its simplicity. Different distributed routing algorithms (DRAs) can be quickly developed by specifying only a few well-defined constraint-dependent parameters within the framework. Our simulation shows that the overhead of the proposed algorithms is stable and modest.

A system and method for routing messages in radiocommunication systems

Abstract: A method and system for improving the routing of messages in a, radiocommunication system are disclosed. In an exemplary system, messages which originate at a mobile unit are routed through both a service center associated with the originating mobile and a service center associated with a recipient mobile. If the recipient has subscribed to an enhanced message routing service, then the home location register returns an address of the recipient's service center in response to a request for routing information. When the home location register is queried again for routing information for the same message, the enhanced message service indicator is suppressed so that the home location register returns a routing number for the equipment which is currently supporting radiocommunication with the recipient, rather than returning the service center address a second time.

Spatial decision support systems for vehicle routing

Abstract: The vehicle routing field is a well-developed area of management science application. There is increasing recognition that effective decision-making in this field requires the incorporation of vehicle routing techniques into a decision support system (DSS). In order to provide decision support for a wide range of problems, routing techniques should be combined with systems that can take advantage of new technologies. These include spatial techniques drawn from the field of geographic information systems (GIS). A synthesis of appropriate algorithms and a GIS based computer system is identified as being necessary for effective decision support for the vehicle routing problem.

Method and apparatus for efficient call routing

Abstract: A method and apparatus to calculate probabilistic routing parameters to more efficiently route telephone calls from an origin to one of a plurality of call centers. In particular, the rate of calls routed to each gate of each call center is measured for a previous time frame and used to estimate the rate of calls routed to input nodes of a routing network from an origin for a next time frame. Using these estimated rates of calls routed to the input nodes, a quadratic programming technique is used to calculate probabilistic routing parameters. These parameters are modified either automatically or by a network manager to improve the routing efficiency.

Per user and network routing tables

Abstract: A gateway is provided which routes a packet sent from a user to a connected network utilizing a per-user routing table. This is accomplished by extracting a source address from the packet; finding a per-user routing table corresponding to the source address, the per-user routing table containing entries corresponding to one or more currently accessible networks for the user and the range of network addresses corresponding to the currently accessible networks; extracting a destination address from the packet; seeking an entry in the matching per-user routing table with a range of network addresses containing the destination address; routing the packet to a matching network if the destination address is contained within one of the ranges of network addresses for the currently accessible networks; and routing the packet to a default network if the destination address is not contained within one of the ranges of network addresses for the currently accessible networks. This allows different users to have access to a different set of networks and allows a user to select the network he wishes to access. The gateway may also guarantee that packet are routed through a particular destination ISP or network by looking up the destination ISP or network in a table, each entry in the table having a router network address corresponding to each network currently accessible; establishing a tunneling session to the matching router network address; and forwarding the packet to the router network address through the tunneling session.

Apparatus and method for routing data packets through a communications network

Abstract: A method and apparatus (25) for determining the next router (25, 26, 27, 28) that a data packet is transmitted to on its way to a destination host (33-35) by traversing a routing table (41) using a hardware search engine (46) and a unique search tree (Fig. 16). The step of traversing each node in the search tree (Fig. 16) takes only one memory cycle, decreasing in half the time it takes to search a routing table (41) and thus forward data packets on a system of computer networks (8). This is accomplished by storing the decision bit for each node in its parent node rather than in the node itself. The apparatus may use a hardware search engine (46) to search the routing table (41).

Apparatus and method of routing data in a radio frequency local area network

Abstract: An apparatus and a method for routing data in a radio data communication system having one or more host computers, one or more intermediate base stations, and one or more RF terminals organizes the intermediate base stations into an optimal spanning-tree network to control the routing of data to and from the RF terminals and the host computer efficiently and dynamically. Communication between the host computer and the RF terminals is achieved by using the network of intermediate base stations to transmit the data.

A general theory for deadlock avoidance in wormhole-routed networks

Abstract: Most machines of the last generation of distributed memory parallel computers possess specific routers which are used to exchange messages between nonneighboring nodes in the network. Among the several technologies, wormhole routing is usually preferred because it allows low channel-setup time and reduces the dependency between latency and internode distance. However, wormhole routing is very susceptible to deadlock because messages are allowed to hold many resources while requesting others. Therefore, designing deadlock-free routing algorithms using few hardware facilities is a major problem for wormhole-routed networks. In this paper, we describe a general theoretical framework for the study of deadlock-free routing functions. We give a general definition of what can be a routing function. This definition captures many specific definitions of the literature (e.g., vertex dependent, input-dependent, source-dependent, path-dependent etc.). Using our definition, we give a necessary and sufficient condition which characterizes deadlock-free routing functions. Our theory embraces, at a high level, most of the theories related to deadlock avoidance in wormhole-routed networks previously derived in the literature. In particular, it applies not only to one-to-one routing, but also to one-to-many routing. The latter paradigm is used to solve the multicast problem with the path-based or tree-based facility.

Apparatus and method for routing communications

Abstract: Telephone calls are routed by means of a routing device (3) which prefixes user generated call numbers with a prefix code which determines a network connection route and provides billing and customer identification information. The device determines the preferred route by addressing a look up table (134, 135) which is periodically updated with updating information transmitted via radio broadcast from a control centre (7). The device is formed unitarily with a mobile telephone (120). The broadcast updating information is transmitted by a message pager transmitting system during off peak message handling times. The device is provided with two memory areas for first and second look up tables (134, 135) so that one of the tables remains addressable while the other one of the tables is being updated with updating information, the most recently updated table being subsequently used as a decision table.

The clade vertebrata: spines and routing in ad hoc networks

Abstract: This work proposes a self-organizing, dynamic infrastructure called a spine for efficient routing in ad hoc networks. We present a scalable framework for routing that encompasses a range of knowledge at each spine node, and identify the trade-offs involved for routing at different points in this range. Our routing algorithm requires only partial topology information at each spine node, consisting of the spine structure, dependants of each spine node, propagation of long-lived links, and snooped routing information from ongoing flows. Through worst-case theoretical bounds and simulation of typical scenarios, we show that the spine-based routing with only partial topology information provides good routes at low overhead.

Method and Apparatus for Routing Calls Based on the Identification of the Calling Party or Calling Line

Abstract: A method and apparatus for routing calls for a subscriber based on the identification of the calling party or the originating line. Generally, the present invention operates to identify a calling party or originating line and then select a routing list based on this identification. Once a routing list has been selected, the call will be routed to the destination in the routing list. More specifically, when a call is received, an inquiry is made regarding the identity of the calling party or calling line. If the identification can be determined, then an attempt to retrieve a routing list associated with this identification is made. If a routing list has been provided for the identified party or line, the routing list will be retrieved. If a routing list has not been provided for the identified party or line, a default routing list will be selected for routing the call.

Interval Routing Schemes

Abstract: Interval routing was introduced to reduce the size of routing tables: a router finds the direction where to forward a message by determining which interval contains the destination address of the message, each interval being associated to one particular direction. This way of implementing a routing function is quite attractive but very little is known about the topological properties that must satisfy a network to support an interval routing function with particular constraints (shortest paths, limited number of intervals associated to each direction, etc.). In this paper we investigate the study of the interval routing functions. In particular, we characterize the set of networks which support a linear or a linear strict interval routing function with only one interval per direction. We also derive practical tools to measure the efficiency of an interval routing function (number of intervals, length of the paths, etc.), and we describe large classes of networks which support optimal (linear) interval routing functions. Finally, we derive the main properties satisfied by the popular networks used to interconnect processors in a distributed memory parallel computer.

The performance of a new routing protocol for the reconfigurable wireless networks

Abstract: In this paper, we investigate the performance of a novel routing protocol, the zone routing protocol (ZRP), that was introduced in Haas (1997). The protocol is targeted at a special class of ad-hoc networks, which we refer to as the reconfigurable wireless networks (RWNs). RWNs are distinguished from other ad-hoc networks by their increased node mobility, larger number of nodes, and wider network span. We demonstrate that ZRP significantly reduces the delay and the amount of routing overhead by providing each node with continuous updates of its local neighborhood (routing zone) topology only. The structure of the routing zone is exploited to efficiently acquire routes on demand for destinations that lie beyond a node's routing zone. By adjusting a single parameter-the size of the routing zone-the ZRP can adapt to a variety of network operational conditions.

K-hop cluster-based dynamic source routing in wireless ad-hoc packet radio network

Abstract: The existing wireless networks, such as cellular networks, personal communication services and mobile Internet protocol use the fixed network as their backbones. However in the situations like disaster rescues, wireless conferences in the hall, or battlefields, there exists no fixed communication infrastructure. Therefore, routing to send data packets to their destinations becomes very difficult. Distance vector and link state protocols used in the existing fixed networks are not suitable for supporting host movements. Variations of distance vector protocol, dynamic source muting schemes, and cluster-based schemes have been suggested to solve the muting problem in this entirely wireless network. However, since the link channel resource is very scarce, the muting scheme must consider the overall channel utilization as well as host mobility. We present a generalized approach called "k-hop cluster-based dynamic source routing". This approach is simple and can take actions on the host movements quickly.

Routing of 100 Gb/s words in a packet-switched optical networking demonstration (POND) node

Abstract: This paper presents the design and experimental results of an optical packet-switching testbed capable of performing message routing with single wavelength time division multiplexed (TDM) packet bit rates as high as 100 Gb/s. The physical topology of the packet-switched optical networking demonstration (POND) node is based on an eight-node ShuffleNet architecture. The key enabling technologies required to implement the node such as ultrafast packet generation, high-speed packet demultiplexing, and efficient packet routing schemes are described in detail. The routing approach taken is a hybrid implementation in which the packet data is maintained purely in the optical domain from source to destination whereas control information is read from the packet header at each node and converted to the electrical domain for an efficient means of implementing routing control. The technologies developed for the interconnection network presented in this paper can be applied to larger metropolitan and wide area networks as well.

Dynamic routing method for packet switched satellite communications

Abstract: A method of routing data packets in a communication network having one or more intelligent routing nodes. Each routing node maintains routing and address resolution information for all nodes within the routing node's domain. Upon detecting a data transmission from a source node to a destination node using a sub-optimal path. The routing node communicates updated routing information to the source node. The source node stores this information such that the subsequent data packets containing the same network address can be transmitted from the source node to the destination node in a single hop.

In-band signaling for routing

Abstract: Telephone call routing in networks is provided by forwarding routing data other than origination identification and destination identification in-band with calls (107), and using the in-band data at call destinations to do further routing In some embodiments negotiation is accomplished between routers (201) at different points in the network (104, 121 and 122) based on the in-band routing data Practice of the invention extends to intelligent telephony networks (100) and as well to simulated telephone calls between computers in wide area data networks, such as the Internet and Intranets