We describe the architecture and implementation of our comprehensive
multi-platform collaboration framework known as Columbia InterNet
Extensible Multimedia Architecture (CINEMA). It provides a
distributed architecture for collaboration using synchronous
communications like multimedia conferencing, instant messaging,
shared web-browsing, and asynchronous communications like discussion
forums, shared files, voice and video mails. It allows seamless
integration with various communication means like telephones,
IP phones, web and electronic mail. In addition, it provides
value-added services such as call handling based on location
information and presence status. The paper discusses the media services needed for collaborative environment, the components
provided by CINEMA and the interaction among those components.
Assisting during emergencies is one of the important functions of the
telephone system. Emergency communications has three components:
summoning help during emergencies, coordinating emergency response and
notifying citizens and public officials of local emergencies. As we transition to an
Internet-based telecommunications system, these functions need to be
provided, but there is also an opportunity to add new functionality and
improve scalability and robustness. We discuss three aspects of
Internet-based communications related to emergencies: First, we
describe how Internet telephony can be used to provide emergency call
(``911'' or ``112'') services. Secondly, Internet telephony needs to be
enhanced to allow prioritized access to communications resources during
emergency-induced network congestion. Finally, Internet event
notification can be a valuable new mechanism to alert communities to
pending or on-going emergencies such as hurricanes or chemical spills.
KEYWORDS: Internet, Glasses, Databases, Data modeling, Data transmission, Analytical research, Pathology, Control systems, Windows 2000, Mathematical modeling
A number of recent studies are based on data collected from routing tables of inter-domain routers utilizing Border Gateway Protocol (BGP) and tools, such as traceroute, to probe end-to-end paths. The goal is to infer Internet topological properties. However, as more data is collected, it becomes obvious that data intended to represent the same properties, if gathered at different points within the network, can depict significantly different characteristics. While systematic data collection from a number of network vantage points can reduce certain ambiguities, thus far, no methods have been reported for fully resolving these issues. The goal of our study was to quantify the effect these anomalies have on key Internet structural attributes. We report on our analysis of over 290,000 measurements from globally distributed sites. We contrast results obtained from router-level measurements with those obtained from BGP routing tables, and offer insights as to why certain inferred properties differ. We demonstrate that the effect on some attributes, such as the average path length and the AS degree distribution can be minimized through careful data collection techniques. We also illustrate how using this same data to model other attributes, such as the actual forwarding path between a pair of nodes, or the level of AS path asymmetry, can produce substantially misleading results.
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