Network topology

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

Measuring ISP topologies with rocketfuel

Abstract: To date, realistic ISP topologies have not been accessible to the research community, leaving work that depends on topology on an uncertain footing. In this paper, we present new Internet mapping t...

The impact of multihop wireless channel on TCP performance

Abstract: This paper studies TCP performance in a stationary multihop wireless network using IEEE 802.11 for channel access control. We first show that, given a specific network topology and flow patterns, there exists an optimal window size W* at which TCP achieves the highest throughput via maximum spatial reuse of the shared wireless channel. However, TCP grows its window size much larger than W* leading to throughput reduction. We then explain the TCP throughput decrease using our observations and analysis of the packet loss in an overloaded multihop wireless network. We find out that the network overload is typically first signified by packet drops due to wireless link-layer contention, rather than buffer overflow-induced losses observed in the wired Internet. As the offered load increases, the probability of packet drops due to link contention also increases, and eventually saturates. Unfortunately the link-layer drop probability is insufficient to keep the TCP window size around W'*. We model and analyze the link contention behavior, based on which we propose link RED that fine-tunes the link-layer packet dropping probability to stabilize the TCP window size around W*. We further devise adaptive pacing to better coordinate channel access along the packet forwarding path. Our simulations demonstrate 5 to 30 percent improvement of TCP throughput using the proposed two techniques.

Topology discovery by active probing

Abstract: As the Internet has grown, so has the challenge of accurate measurement and modeling of its topology. Commonly used but coarse methods of measuring topology, e.g., BGP tables, suffer from several limitations. To pursue more accurate empirically-based topology modeling, in 1998 CAIDA began its Macroscopic Topology Project, which focuses on actively measuring topology and round trip time (RTT) information across a large cross-section of the commodity Internet. We describe CAIDA's topology measurement architecture and our analysis and visualization tools. We describe differences between IP and AS (BGP-based) granularities of topology modeling, including advantages and limitations of both, as well as how correlation between both types of data can yield more relevant insights. We introduce four new visualization metaphors for handling macroscopic topology data, as well as a tool for aggregating multiple IP addresses into the same physical router. We highlight results of our analyses, in particular relationships between RTT and topology data, and how source and destination selection and geopolitical boundaries affect those relationships.

Detecting Critical Nodes in Interdependent Power Networks for Vulnerability Assessment

Abstract: Power networks and information systems become more and more interdependent to ensure better supports for the functionality as well as improve the economy. However, power networks also tend to be more vulnerable due to the cascading failures from their interdependent information systems, i.e., the failures in the information systems can cause the failures of the coupled portion in power networks. Therefore, the accurate vulnerability assessment of interdependent power networks is of great importance in the presence of unexpected disruptive events or adversarial attacks targeting on critical network nodes. In this paper, we study the Interdependent Power Network Disruptor (IPND) optimization problem to identify critical nodes in an interdependent power network whose removals maximally destroy its functions due to both malfunction of these nodes and the cascading failures of its interdependent communication network. First, we show the IPND problem is NP-hard to be approximated within the factor of (2-e) . Despite its intractability, we propose a greedy framework with novel centrality functions based on the networks' interdependencies, to efficiently solve this problem in a timely manner. An extensive experiment not only illustrates the effectiveness of our approach on networks with different topologies and interdependencies, but also highlights some important observations which help to sharpen the robustness of interdependent networks in the future.

Fiber-wireless (FiWi) access networks: A survey

Abstract: This article provides an up-to-date survey of hybrid fiber-wireless (FiWi) access networks that leverage on the respective strengths of optical and wireless technologies and converge them seamlessly. FiWi networks become rapidly mature and give rise to new powerful access network solutions and paradigms. The survey first overviews the state of the art, enabling technologies and future developments of wireless and optical access networks, respectively, paying particular attention to wireless mesh networks and fiber to the home networks. After briefly reviewing some generic integration approaches of EPON and WiMAX networks, several recently proposed FiWi architectures based on different optical network topologies and WiFi technology are described. Finally, technological challenges toward the realization and commercial adoption of future FiWi access networks are identified.