Dial-up Connections Research Articles

PC broadband security

The only real disadvantage to broadband is something generally overlooked by the average Internet user, i.e. security. The always on, high bandwidth, connection that cable modems and DSL lines give their users make them alluring targets for unscrupulous people more so than slow dial-up connections.

Relevance and Priorities of ICT for Women in Rural Communities: A Case Study from Nigeria

Relevance and Priorities of ICT for Women in Rural Communities: A Case Study from Nigeria

Modeling dialup internet access: an examination of user-to-modem ratios, blocking probability, and capacity planning in a modem pool

In the near future, dialup connections will remain as one of the most popular methods of remote access to the Internet as well as to enterprise networks. The dimensioning of modem pools to support this type of access is of particular importance to commercial Internet service providers as well as to universities that maintain their own modem pools to support access by faculty, staff, and students. The primary contribution of this paper is to analyze how network administrators may decrease the probability of blocking for access to the pool by imposing session limits restricting the maximum duration of the online session. Session limits may provide a viable alternative to improving network performance without necessarily adding capacity to the pool. Blocking probability is examined under a number of different scenarios to assess potential improvements in the quality of service by imposing session limitations during peak-period operations. Scope and purpose The dimensioning of modem pools to support dialup access by subscribers is an important problem facing both Internet service providers (ISP) and academic institutions that support this type of access. This paper focuses on the use of computer simulation to address modem pool performance using blocking probability as a proxy for level of service during peak periods of operation. The parameter estimates for network traffic are based on historical session log data from large university-based ISP. The paper begins with a brief discussion of traffic variables and examines the underlying distributions associated with each variable. A simulation model is constructed using OPNET Technologies network modeling tool, OPNET Modeler TM. The results of the various simulations are presented and discussed in detail. Long-range capacity planning in dialup environments is critical despite the fact that network-related research has shifted away from dialup issues and focused on more cutting-edge issues. Although dialup network access remains the most heavily utilized consumer-based access method in the world, few providers seem to be considering issues such as the level of service provided to customers and how they may be able to improve service. We examine the issue of service quality in terms of the probability of blocking. Once a benchmark blocking probability is calculated for the modem pool, we investigate how the implementation of innovative management strategies, such as imposing session limits, may impact blocking vs. the traditional approach of simply adding capacity. The paper seeks to provide readers with some indication as to the level of service associated with various user-to-modem ratios and how different combinations of session limits and capacity may improve service.

Multimedia learning systems: a future interactive educational tool

The authors outline in this paper the enhancement of a learning technique by the deployment of a novel multimedia learning system (MMLS). An overview of MMLS starting from the content development flow to the implementation stage is discussed in detail. This project is currently being launched at the Multimedia University (MMU) Malaysia. Macromedia Dreamweaver and Macromedia Flash were used to develop the interactive environment within the two campuses in MMU. In addition, a borderless education scenario is proposed by accessing the MMLS web site at http://mmls.mmu.edu.my/, through a T1 connection and Internet browser at the office as well as through slower connection speeds such as the common 28.8 kbps dial-up connection from off-campus sites.

AAA: a survey and a policy-based architecture and framework

The commercialization of the Internet has led to a large variety of business models based on Internet technology. Therefore, the demand for standardized and efficient solutions in support of reliable, secure, open, and flexible remote and mobile service accesses has increased. Existing authentication, authorization, and accounting systems still consider dedicated cases, but lack a generic approach. More general AAA services can be built by extending existing mechanisms and protocols for access scenarios other than dialup or PPP connections. While this work is performed mainly by the IETF AAA Working Group, another approach proposed by the IRTF AAAArch Research Group is termed AAA Architecture. This article surveys the state of the art in AAA and develops a new generic policy-based approach, A/sup x/, for AAA services and beyond, considering flexible levels of various services in an Internet service model, ranging from connectivity to content services.

Reliable sources of anthrax information online

The web has emerged as an especially useful information resource for users wishing to keep abreast of investigations into the deliberate release of anthrax in the USA and elsewhere. The US National Institutes of Health posts related press briefings and conferences on its videocast site (videocast.nih.gov/ PastEvents.asp?c=4), often within hours of the actual event. Of particular interest here are the Oct 23 press conference, Anthrax: what every clinician should know, in which Anthony Fauci and others discuss relevant articles published in Nature(www.nature.com), and the Oct 18 US Centers for Disease Control and Prevention's (CDC) briefing, Information about the current anthrax investigations(transcript available at www.cdc.gov/od/oc/media/transcripts/t011026.htm). Videocasts are in RealPlayer format and run well even over a dialup connection. Continuously updated news stories related to anthrax are posted on the Associated Press wire service site (www.sj-r.com/news/wire/apwire.htm); also check Headline Spot (www.headlinespot.com), an easy-to-navigate portal that provides links to hundreds of newspapers worldwide (search on “anthrax” for current articles). The following is a roundup of additional noteworthy sites that provide scientific background, patient information, and other materials geared specifically to health professionals. Be sure to check the “links” section of each site for additional resources. The web has emerged as an especially useful information resource for users wishing to keep abreast of investigations into the deliberate release of anthrax in the USA and elsewhere. The US National Institutes of Health posts related press briefings and conferences on its videocast site (videocast.nih.gov/ PastEvents.asp?c=4), often within hours of the actual event. Of particular interest here are the Oct 23 press conference, Anthrax: what every clinician should know, in which Anthony Fauci and others discuss relevant articles published in Nature(www.nature.com), and the Oct 18 US Centers for Disease Control and Prevention's (CDC) briefing, Information about the current anthrax investigations(transcript available at www.cdc.gov/od/oc/media/transcripts/t011026.htm). Videocasts are in RealPlayer format and run well even over a dialup connection. Continuously updated news stories related to anthrax are posted on the Associated Press wire service site (www.sj-r.com/news/wire/apwire.htm); also check Headline Spot (www.headlinespot.com), an easy-to-navigate portal that provides links to hundreds of newspapers worldwide (search on “anthrax” for current articles). The following is a roundup of additional noteworthy sites that provide scientific background, patient information, and other materials geared specifically to health professionals. Be sure to check the “links” section of each site for additional resources.

The Shape of Things to Come

The Shape of Things to Come

Design of an SHD-distributed database over IP to support telemedicine.

We have conducted tests utilizing superhigh-definition CRTs (hereafter, referred to as a "super high-definition image system," or "SHD ": 2,048 x 2,048 pixels, 24-bit RGB gradation, noninterlace system) for autonomous and distributed medical image database systems. The system is capable of providing six times the image definition of a hi-vision television (HDTV). The aim in designing and testing the system is to enable gigabit network connectivity while displaying images on a DOS- V machine. This paper discusses how we devised an integrated environment for managing and operating distributed an SHD image database to support Telemedicine linking with ATM, with INS-1500, and with dial-up IP connection.

Choosing an Internet service provider

For most people, a telephone line (dial-up) connection is the only economic way of connecting their computer to the Internet from home. Most homes already have a telephone line installed, and you can buy a modem for under £100 (if your PC wasn't supplied with one). This is all the hardware you need to connect to the Internet, but you also need an internet service provider (ISP).

Performance evaluation of telecommunication systems with forcible cutoff control scheme

The rapid growth of computer-communication services means that telephone-conversation traffic must compete for system resources with computer-communication traffic carried by dial-up connections to the Internet or intranets over public telephone switching networks. The traffic characteristics differ for the two types of service; for example, the mean holding time and peak traffic periods are different. However, because dial-up connection calls occupy circuit lines for a long time, the grade of service (GoS) of telephone-conversation calls may deteriorate during periods of peak demand. Another problem is that since a telephone switching network is dimensioned to satisfy the required GoS for telephone calls during peak demand periods, there will be surplus resources, and a significant opportunity cost, during off-peak periods. One way to efficiently use these surplus switching-network resources is to offer fixed-cost best-effort dial-up connection service during off-peak periods for telephone traffic. This also makes the demand for dial-up connections less likely to affect the GoS of telephone-conversation calls during peak periods. We propose a priority control scheme for such an off-peak service. This scheme works as follows in a telephone switching system where both high-priority telephone-conversation calls and low-priority dial-up connection calls are offered. When a call arrives at the system and there are adequate resources available for an ordinary telephone-conversation call, a high-priority telephone call or a low-priority dial-up connection call can be connected. However, if a high-priority call arrives at the system and there are not enough resources available to allow connection, an already connected dial-up connection call is forcibly cut off to enable connection of the high-priority telephone call, and thus guarantee the GoS of telephone calls. We evaluate the performance of a telecommunication system based on this scheme by using a Markov model. We derive the call-blocking probabilities for both call types and the ratio of the amount of traffic that is forcibly cut off to the amount of offered traffic in the system, and show calculated results. We also discuss some guidelines for offering services using this scheme. © 2000 Scripta Technica, Electron Comm Jpn Pt 1, 83(6): 78–87, 2000

Satellite Internet services using DVB/MPEG-2 and multicast Web caching

Communication satellites can be used to broadcast large volumes of data directly to extensive user groups. With the latest generation of high-powered direct broadcast satellites and the changing traffic and usage patterns in the Internet, new ways of using satellites for delivering data directly to the end user have become viable alternatives to terrestrial point-to-point networks. In this article the software architecture of a distributed system, which has been successfully implemented and which supports online and offline interactive multimedia services, is presented. It is based on a method of carrying Internet datagrams over DVB/MPEG-2 transport systems, intended for digital television. It relies on a configuration using a broadband forward channel and a separate, usually narrowband, return channel. The forward link is usually provided by a geostationary satellite, whereas the return channel uses a different network technology, such as dialup connection, a direct Ku-band return link, a LEO satellite network, or an LMDS local distribution system. A generic multicast system is presented which exploits the inherent capabilities of satellites to reach a large number of customers. The reliable multicast strategy chosen is shown to handle multiple applications, each with different reliability and timing requirements.

Current Awareness Using PubMed

ABSTRACT Current awareness is something that librarians do, at least informally, passing on relevant current information to their patrons on a regular basis. The type of current awareness service considered here entails running preselected searches against electronic databases. The availability of these electronic bibliographic databases allows automating much of the current awareness process. Any successful current awareness service will have three key attributes: speed, ease of use, and relevance. The flexibility and accessibility of the National Library of Medicine's PubMed make it ideal as the basis for a current awareness service. Six freely available services are evaluated according to uniform criteria with notes made of special features. Four services use PubMed as the source for data, and the other two use MEDLINE. Recommendations are made for modifying one of the services to embody the key attributes of a successful service. Particular attention is given to local needs. Such a service can be run from a single desktop machine with a dial-up connection to the Internet.

Universal media

Universal Media is a Web3D consortium working group solution that increases the realism of on-line Web3D worlds (VRML, Java 3D and other on-line 3D technologies). It also decreases network downloads by defining a small, cross-platform library of locally resident media elements (textures, sounds, 3D objects and filters) and a uniform resource name (URN) mechanism by which Web3D content creators can incorporate these media elements into their worlds. Universal Media allows content authors to create media-rich worlds that can be instantly loaded over even the slowest dial-up modem Internet connections. Fully compatible with standard VRML browsers, Universal Media conforms to the VRML97 specification, allowing media-rich worlds to load 20 to 50 times faster on average without deviating from industry standards.Because Universal Media is stored on the user's hard drive (or other local storage), content authors can use Universal Media just as they do local resources, without concern for downloading each media element over a network connection. This simple but powerful concept allows multi-megabyte, media-rich worlds such as the one illustrated in Figure 1 to load almost instantly over even the slowest network connections.In this respect, Universal Media can be thought of as a locally resident suite of 3D media primitives, or media building blocks, that enable Web3D content developers to construct realistic looking and sounding worlds without the penalty of network transfers typically associated with media-rich worlds. And, since the media elements that ultimately make up the Universal Media library are expected to be of extremely high quality, Web3D content developers will be able to build compelling worlds in considerably less time and at an overall lower cost than if they were to create such media themselves.Specifically, the Web3D Consortium's Universal Media Working Group ( http://www.web3d.org/Working-Groups/media/ mirrored at http://www.web3dmedia.com/ ) is defining cross-platform media libraries comprised of textures, sounds and 3D objects that reside on the client (end-user) computer systems. In addition, the Universal Media Working Group is defining a standard media filter mechanism that allows such content to be dynamically transformed using predefined, yet customizable, filters (a morph filter might dynamically morph the geometry of a 3D cat object into a lion, for example, while a ripple filter might animate a grass texture so that it appears to ripple in the wind).Universal Media is distributed freely through the Web3D Consortium. At the time of this writing, version 1.0 of the Textures library (Textures 1.0) has been released, while sounds and 3D objects are scheduled for release in mid-2000. Universal Media filters are currently under development, and the first library of pre-made filters is expected to ship in late 2000.

Measurement-based modelling of Internet dial-up access connections

The traffic generated by dial-up access to the Internet is a major cause of overload on the telephone network, spurring the need for call level traffic characterization. The results of a measurement campaign on calls directed to Internet Service Providers are here used to analyze models for their arrival process and for their holding time. The arrival process can be described by a Poisson model but with a variable mean frequency of arrivals within the hour. The hyperexponential model is selected for the probability density function of the call holding times, with mean value of about 15 min most of the day.

CIS3/398: Implementation of a Web-Based Electronic Patient Record for Transplant Recipients

IntroductionWhile the "Electronic patient record" (EPR) is a frequently quoted term in many areas of healthcare, only few working EPR-systems are available so far. To justify their use, EPRs must be able to store and display all kinds of medical information in a reliable, secure, time-saving, user-friendly way at an affordable price. Fields with patients who are attended to by a large number of medical specialists over a prolonged period of time are best suited to demonstrate the potential benefits of an EPR. The aim of our project was to investigate the feasibility of an EPR based solely on "of-the-shelf"-software and Internet-technology in the field of organ transplantation.MethodsThe EPR-system consists of three main elements: Data-storage facilities, a Web-server and a user-interface. Data are stored either in a relational database (Sybase Adaptive 11.5, Sybase Inc., CA) or in case of pictures (JPEG) and files in application formats (e. g. Word-Documents) on a Windows NT 4.0 Server (Microsoft Corp., WA). The entire communication of all data is handled by a Web-server (IIS 4.0, Microsoft) with an Active Server Pages extension. The database is accessed by ActiveX Data Objects via the ODBC-interface. The only software required on the user's computer is the Internet Explorer 4.01 (Microsoft), during the first use of the EPR, the ActiveX HTML Layout Control is automatically added. The user can access the EPR via Local or Wide Area Network or by dial-up connection. If the EPR is accessed from outside the firewall, all communication is encrypted (SSL 3.0, Netscape Comm. Corp., CA).The speed of the EPR-system was tested with 50 repeated measurements of the duration of two key-functions: 1) Display of all lab results for a given day and patient and 2) automatic composition of a letter containing diagnoses, medication, notes and lab results. For the test a 233 MHz Pentium II Processor with 10 Mbit/s Ethernet connection (ping-time below 10 ms) over 2 hubs to the server (400 MHz Pentium II, 256 MB RAM) was used.ResultsSo far the EPR-system has been running for eight consecutive months and contains complete records of 673 transplant recipients with an average follow-up of 9.9 (SD :4.9) years and a total of 1.1 million lab values. Instruction to enable new users to perform basic operations took less than two hours in all cases. The average duration of laboratory access was 0.9 (SD:0.5) seconds, the automatic composition of a letter took 6.1 (SD:2.4) seconds. Apart from the database and Windows NT, all other components are available for free. The development of the EPR-system required less than two person-years.ConclusionImplementation of an Electronic patient record that meets the requirements of comprehensiveness, reliability, security, speed, user-friendliness and affordability using a combination of "of-the-shelf" software-products can be feasible, if the current state-of-the-art internet technology is applied.

The commissioning

The installation, in a noisy, dusty, poorly lit underground experimental hall, was hard going. Then the technicians went home, leaving three engineers to commission it, and that was worse. I found that a helpful therapy was to sit down in the evening and send an E-mail back to base, trying to convey a little of the day's work. I should explain that this was a few years ago, when E-mail was more of a novelty than it is now. I had a terminal in my hostel room, but back at base there was just a shared dial-up connection, so my messages were printed and put on a notice board. As a reminder to managers of what life can be like in the field, here are the E-mails of the final two weeks. I hope enough time has passed that they will not cause embarrassment, and of course I have changed the names, but the story really is true. The project was a large superconducting magnet, supplied to APPL (American Particle Physics Laboratory).

AAA protocols: authentication, authorization, and accounting for the Internet

Internet service providers (ISPs) offering dial-up access and purveyors of enterprise networks supporting telecommuters face some difficult challenges. Ever-increasing residential dialup subscribers demand available modem (or ISDN) ports, or threaten to take their business elsewhere. To meet this demand, ISPs (dial providers) are deploying a large number of-complex, port-dense network access servers (NAS) to handle thousands of individual dial-up connections. At the same time, the miniaturization of stationary office essentials, such as the laptop computer and cellular telephone, has coupled with the need for maximum customer face time to create a workforce in perpetual motion. These "road warriors" require secure and reliable access to email and Web resources from hotels, airports, and virtual offices around the world. But dial providers must do more than simply offer an available modem port at the other end of a telephone call. They must protect against theft-of-service attacks by unscrupulous individuals with excess free time; they must verify subscribers' levels of access authorization; and for cost recovery, billing, and resource planning purposes, they may need to meter the connection time to the network. Furthermore, to provide maximum coverage to a growing roaming and mobile subscriber base, they may choose to pool their NAS resources while retaining control over their subscribers' access, usage, and billing information. All these services require coordination between the various administrative systems supported by the dial providers in partnership with each other.

Real-time audio and video broadcasting of IEEE GLOBECOM '96 over the Internet using new software

This article describes the experience of the authors transmitting real-time audio and video of IEEE Global Internet '96, a mini-conference at IEEE GLOBECOM '96 over the Internet with new software called SoftwareVision. SoftwareVision (http://www.hil.ntt.jp/Softwarevision) was used in parallel with the Mbone for this first experiment of the IEEE Communications Society. The main reason for this was to cover not only users at universities and laboratories (Mbone users) but also those at enterprises and homes (even dial-up users). Since the number of users who could access the Mbone were limited, SoftwareVision provided other users with the opportunity to participate in this exciting event. The event was broadcast all over the world, so some users, particularly those on the opposite side of the world, stayed at home (till very late at night) and could see and hear the conference by dial-up connections. The quality of the video was satisfactory enough for them to listen to what the speakers said and see the slides of the overhead projections. The accumulated number of users who accessed this two-day event was 353. This shows there is enough potential demand for remote participation in the conference. This broadcasting was initiated by the members of the IEICE (Institute of Electronics. Information, and Communications Engineers).

Virtual private networks: leveraging the Internet

Proponents say virtual private networks could be the wave of the networking future for one very important reason: VPNs transmit data via the Internet, rather than via expensive traditional private networks. Proponents are quick to mention the significant cost savings organizations can realize by using networks that employ the Internet backbone as a data pipeline rather than networks that rely on leased lines, frame-relay technology, and dialup connections for private WANs. However, as with many Internet technologies, potential VPN users are concerned about possible security, reliability, and performance problems. ln addition, a lack of open standards has created concerns about compatibility. The industry is working toward adoption of such standards, but it remains to be seen whether this will lend credibility to VPN technology.

Emergency Medicine: Intensive Care and Cyberspace

Emergency Medicine: Intensive Care and Cyberspace