Network topology

About: Network topology is a research topic. Over the lifetime, 52259 publications have been published within this topic receiving 1006627 citations.

Robustness and network evolution--an entropic principle

Abstract: This article introduces the concept of network entropy as a characteristic measure of network topology. We provide computational and analytical support for the hypothesis that network entropy is a quantitative measure of robustness. We formulate an evolutionary model based on entropy as a selective criterion and show that (a) it predicts the direction of changes in network structure over evolutionary time and (b) it accounts for the high degree of robustness and the heterogenous connectivity distribution, which is often observed in biological and technological networks. Our model is based on Darwinian principles of evolution and preferentially selects networks according to a global fitness criterion, rather than local preferences in classical models of network growth. We predict that the evolutionarily stable states of evolved networks will be characterized by extremal values of network entropy.

Integrated dynamic IP and wavelength routing in IP over WDM networks

Abstract: This paper develops an algorithm for integrated dynamic routing of bandwidth guaranteed paths in IP over WDM networks. By integrated routing, we mean routing taking into account the combined topology and resource usage information at the IP and optical layers. Typically, routing in IP over WDM networks has been separated into routing at the IP layer taking only IP layer information into account, and wavelength routing at the optical layer taking only optical network information into account. The motivation for integrated routing is the potential for better network usage, and this is a topic which has not been been studied extensively. We develop an integrated routing algorithm that determines (1) whether to route an arriving request over the existing topology or whether it is better to open new wavelength paths. Sometimes it is better to open new wavelength paths even if it feasible to route the current demand over the existing IP topology due to previously set-up wavelength paths. 2) For routing over the existing IP-level topology, compute "good" routes. (3) If new wavelength paths are to be set-up, determine the routers amongst which new wavelength paths are to be set-up and compute "good" routes for these new wavelength paths. The performance objective is the accomodation of as many requests as possible without requiring any a priori knowledge regarding future arrivals. The route computations account for the presence or absence of wavelength conversion capabilities at optical crossconnects. We show that the developed scheme performs very well in terms of performance metrics such as the number of rejected demands.

The Internet AS-Level Topology: Three Data Sources and One Definitive Metric

Abstract: We calculate an extensive set of characteristics for Internet AS topologies extracted from the three data sources most frequently used by the research community: traceroutes, BGP, and WHOIS. We discover that traceroute and BGP topologies are similar to one another but differ substantially from the WHOIS topology. Among the widely considered metrics, we find that the joint degree distribution appears to fundamentally characterize Internet AS topologies as well as narrowly define values for other important metrics. We discuss the interplay between the specifics of the three data collection mechanisms and the resulting topology views. In particular, we show how the data collection peculiarities explain differences in the resulting joint degree distributions of the respective topologies. Finally, we release to the community the input topology datasets, along with the scripts and output of our calculations. This supplement should enable researchers to validate their models against real data and to make more informed selection of topology data sources for their specific needs.

Consensus of Multiagent Systems Subject to Partially Accessible and Overlapping Markovian Network Topologies

Abstract: This paper addresses the consensus problem for a continuous-time multiagent system (MAS) with Markovian network topologies and external disturbance. Different from some existing results, global jumping modes of the Markovian network topologies are not required to be completely available for consensus protocol design. A network topology mode regulator (NTMR) is first developed to decompose unavailable global modes into several overlapping groups, where overlapping groups refer to the scenario that there exist commonly shared local modes between any two distinct groups. The NTMR schedules which group modes each agent may access at every time step. Then a new group mode-dependent distributed consensus protocol on the basis of relative measurement outputs of neighboring agents is delicately constructed. In this sense, the proposed consensus protocol relies only on group and partial modes and eliminates the need for complete knowledge of global modes. Sufficient conditions on the existence of desired distributed consensus protocols are derived to ensure consensus of the MAS with a prescribed $H_{\infty }$ performance level. Two examples are provided to show the effectiveness of the proposed consensus protocol.

Express Cube Topologies for on-Chip Interconnects

Abstract: Driven by continuing scaling of Moore's law, chip multi-processors and systems-on-a-chip are expected to grow the core count from dozens today to hundreds in the near future. Scalability of on-chip interconnect topologies is critical to meeting these demands. In this work, we seek to develop a better understanding of how network topologies scale with regard to cost, performance, and energy considering the advantages and limitations afforded on a die. Our contributions are three-fold. First, we propose a new topology, called Multidrop Express Channels (MECS), that uses a one-to-many communication model enabling a high degree of connectivity in a bandwidth-efficient manner. In a 64-terminal network, MECS enjoys a 9% latency advantage over other topologies at low network loads, which extends to over 20% in a 256-terminal network. Second, we demonstrate that partitioning the available wires among multiple networks and channels enables new opportunities for trading-off performance, area, and energy-efficiency that depend on the partitioning scheme. Third, we introduce Generalized Express Cubes - a framework for expressing the space of on-chip interconnects - and demonstrate how existing and proposed topologies can be mapped to it.