Information Dynamics Applied to Link-State Routing (original) (raw)
Related papers
Some Comments on Highly Dynamic Network Routing
1988
Attempting to dynamically adapt network parameters to the load seen can produce unexpected results. We present a simple model network example which demonstrates unstable behavior when traffic is directed according to routing optimized for minimal delay and the load varies at a rate comparable to the routing calculation time. The instability can be avoided by using almost any alternate design which avoids the knees on the delay curves, e.g. a Maximum Entropy Method design. The delay penalty in this case turns out to be small. This paper is very mathematical, but the point is simple: attempting make network parameters change as quickly as possible may not be an appropriate network management strategy.
Routing Bandwidth Constrained Applications under Inaccurate Network State Information
In large dynamic networks it is extremely difficult to maintain accurate network state information on all network nodes. Different causes motivate this inaccuracy, the state aggregation produced in hierarchical networks, the delay in flooding the network state information, or the triggering policy used to determine when updating this network state information. In the current Internet (IP/MPLS), new QoS routing mechanisms addressing this problem are being investigated. After reviewing the recent most significant contributions on this topic, this paper focuses on the Bypass-based Routing (BBR) mechanism, a QoS routing mechanism aiming to reduce the effects of the routing inaccuracy problem when considering bottleneck requirements in an IP/MPLS network. This paper consolidates the BBR proposal by addressing open issues related to scalability and efficiency turning out the Optimized BBR (OBBR). Results obtained by simulation conclude that the OBBR might be widely used as a routing mechanism for bandwidth constrained applications aiming to reduce the negative effects due to selecting paths under inaccurate network state information.
Routing in a delay tolerant network
ACM SIGCOMM Computer Communication …, 2004
We formulate the delay-tolerant networking routing problem, where messages are to be moved end-to-end across a connectivity graph that is time-varying but whose dynamics may be known in advance. The problem has the added constraints of finite buffers at each node and the general property that no contemporaneous end-to-end path may ever exist. This situation limits the applicability of traditional routing approaches that tend to treat outages as failures and seek to find an existing end-to-end path. We propose a framework for evaluating routing algorithms in such environments. We then develop several algorithms and use simulations to compare their performance with respect to the amount of knowledge they require about network topology. We find that, as expected, the algorithms using the least knowledge tend to perform poorly. We also find that with limited additional knowledge, far less than complete global knowledge, efficient algorithms can be constructed for routing in such environments. To the best of our knowledge this is the first such investigation of routing issues in DTNs.
Integrating local static and dynamic information for routing traffic
Physical Review E, 2006
The efficiency of traffic routing on complex networks can be reflected by two key measurements, i.e., the network capacity and the average travel time of data packets. In this paper we propose a mixing routing strategy by integrating local static and dynamic information for enhancing the efficiency of traffic on scale-free networks. The strategy is governed by a single parameter. Simulation results show that maximizing the network capacity and reducing the packet travel time can generate an optimal parameter value. Compared with the strategy of adopting exclusive local static information, the new strategy shows its advantages in improving the efficiency of the system. The detailed analysis of the mixing strategy is provided for explaining its effects on traffic routing. The work indicates that effectively utilizing the larger degree nodes plays a key role in scalefree traffic systems.
Link Modeling and Delay Analysis in Networks with Disruptive Links
ACM Transactions on Sensor Networks, 2017
Delay-and Disruption-Tolerant Networks (DTNs) refer to a range of networks with link intermittency that is mainly driven by mobility, predictable or unpredictable network environmental conditions. Examples of DTNs include interplanetary networks, battlefield networks, smart highways, remote sensing, and animal-movement outposts. There exist a number of mobility models describing the operation of various DTNs. One common characteristic that all mobility models share is the distribution of contact time and inter-contact time between nodes. Predicting an end-to-end delay in networks with disruptive links is more complicated than predicting the delay in connected networks. Disruptive patterns and underlying routing algorithms play a major role in an end-to-end delay modeling. In this article, we introduce a new model that can be used to estimate the end-to-end delay in networks with intermittent links. The model incorporates the two non-deterministic delay distributions, namely link intermittency and tandem queuing delay distributions. The model is based on an open queuing system with exponentially distributed link intermittency. The model gives a close approximation of the average end-to-end delay and the delay variance in closed forms. Simulation results on various networks and under different traffic conditions confirm the accuracy of the model within the conventional bounds of statistical significance. 1 INTRODUCTION Delay-and Disruption-Tolerant Networks (DTNs) are special-purpose networks where an end-to-end connectivity does not exist at all times and messages are routed in a store-carry-and-forward fashion. While the demand for DTNs initially emerged in the area of space communication networks (Cerf et al. 2007; Scott and Burleigh 2007), new applications of DTNs have recently developed in other areas of networking, including battle field networks, smart highways, remote sensing, and animal-movement outposts. These networks all share the same major characteristic: link intermit-tency. Other characteristics include long or variable delay, asymmetric data rates, and high error rates. Link intermittency can be periodic (deterministic) or sporadic (non-deterministic). In sensor networks, transmitters can be turned off and on to conserve energy in predictable manner or based
A traffic engineering approach based on minimum-delay routing
Proceedings Ninth International Conference on Computer Communications and Networks (Cat.No.00EX440), 2000
Single-path routing provided by today's Interior Gateway Protocols (IGPs) make extremely inefficient usage of network bandwidth, and is evident in the large end-to-end delays flows experience in single-path routing as compared to minimum-delay routing. Enhancement to OSPF such as optimized multipath have not proved adequate to bridge this large delay gap. Practical implementation of minimum-delay routing, on the other hand, have been largely unsuccessful for reasons such as scalability, slow convergence and out-of-order packet delivery. This paper proposes a traffic engineering solution that adapts the minimum-delay routing for a given traffic matrix in a way that is practical and suitable to implement in the Differential Services framework. A simple and scalable packet forwarding technique is described that offers several improvements over OSPF-OMP.
Practical routing in delay-tolerant networks
2005
Delay-tolerant networks (DTNs) have the potential to connect devices and areas of the world that are under-served by current networks. A critical challenge for DTNs is determining routes through the network without ever having an end-to-end connection, or even knowing which "routers" will be connected at any given time. Prior approaches have focused either on epidemic message replication or on knowledge of the connectivity schedule. The epidemic approach of replicating messages to all nodes is expensive and does not appear to scale well with increasing load. It can, however, operate without any prior network configuration. The alternatives, by requiring a priori connectivity knowledge, appear infeasible for a self-configuring network.
Synthèse : Revue des Sciences et de la Technologie, 2016
The calculation of the shortest path between a pair of routers is an important problem in telecommunication and computer networks. The calculation of the path in real time is useful in a number of situations. These include a routing process that attempts to reach its destination and minimizing the effects of collision with obstacles. Previous works on the shortest path are limited to sequential and parallel algorithms on general-purpose architectures. Researchers are increasingly interested in hardware's solutions. In this work , we propose an approach for implementing a routing algorithm which is effective than Dijkstra using a FPGA development board Xilinx Virtex-type order accelerate the process of routing based on the speed of hardware (FPGA). The results of the implementation in an FPGA card Virtex7 are promising.
Evaluating the impact of stale link state on quality-of-service routing
IEEE/ACM Transactions on Networking, 2001
Quality-of-service (QoS) routing satisfies application performance requirements and optimizes network resource usage by selecting paths based on connection traffic parameters and link load information. However, distributing link state imposes significant bandwidth and processing overhead on the network. This paper investigates the performance trade-off between protocol overhead and the quality of the routing decisions in the context of the source-directed, link-state routing protocols proposed for IP and ATM networks. We construct a detailed model of QoS routing that parameterizes the path-selection algorithm, link-cost function, and link-state update policy. Through extensive simulation experiments with several network topologies and traffic patterns, we uncover the effects of stale link-state information and random fluctuations in traffic load on the routing and set-up overheads. We then investigate how inaccuracy of linkstate information interacts with the size and connectivity of the underlying topology. Finally, we show that tuning the coarseness of the link-cost metric to the inaccuracy of underlying link-state information reduces the computational complexity of the path-selection algorithm without significantly degrading performance. This work confirms and extends earlier studies, and offers new insights for designing efficient quality-of-service routing policies in large networks.
"An Analysis of Convergence Delay in Path Vector Routing Protocols"
Path vector routing protocols such as the Border Gateway Protocol (BGP) are known to suffer from slow convergence following a change in the network topology or policy. Although a number of convergence enhancements have been proposed recently, there has been no general analytical framework to assess and compare the various proposed algorithms. In this paper we present such a general framework to analyze the upper bounds of path vector protocolsÕ convergence delay under shortest path routing policy and single link failure. Our framework takes into account important factors such as network connectivity, failure location, and routing message processing delay. It can be used to analyze both standard BGP and all the proposed convergence improvement algorithms in the case of shortest path routing policy and single link failure. It enables us to obtain previously unavailable analytical results, including the delay bounds of path fail-over for standard BGP and its convergence enhancements. Our analysis shows that BGP fail-over delay bounds are mainly determined by two factors: (1) the distance between the failure location and the destination, and (2) the length of the longest alternate path to reach the destination after the failure. These two factors are captured formally by our analysis and can explain why existing convergence enhancements often provide only limited improvements in fail-over events. Moreover, explicitly modeling message processing delay reveals insights into the impacts of connectivity richness (i.e., node degree and total number of links in the network), and also the effectiveness of different enhancements. These new results enable one to better understand and compare the behavior of various path vector protocols under different topology structures, network sizes, and message delays.