Local Access Networks

WiFi (802.11) has emerged as another brisk growth driver for semiconductors, as Wireless Local Access Networks (WLAN) are spreading rapidly around the world. The compound annual growth rate of WLAN is expected to exceed 35% over the 2000-2005 forecast period. 

To our knowledge, the first wireless communication adopted was based on infrared technology (Kahn Barry, 1997), due to the low cost of infraredcommimication devices. Radio Frequency (RF) rapidly replaced infrared technology, due to the increased use of Internet wireless Local Access Networks (LANs) (IEEE 802.11). In robotics, Wi-Fi Networks serve as a backbone for data concentration and networking. They are used in conjunction with short-range, low-power devices in a wireless field network to collect data from... 

ISI is available in hard copy and electronically at EPA s headquarters and regional Hbraries, and through the National Technical Information Service (NTIS). The electronic form may be installed on IBM PC-compatible computers or placed on local area networks, and mn under Microsoft WINDOWS or WordPerfect s Library program. The Macintosh version is no longer available. The 1993 update will include the ISI hardcopy, PC disks, and the PC system user manual. EPA also pubHshes ACCESS EPA, which provides sources of information, databases, and pubHcations within the EPA. Chapter 5 of that pubhcation includes important environmental databases in air and soHd waste, pesticides and toxic substances, water, and cross-program (110). EPA also provides databases accessible through EPA Hbraries, which describe the private EPA and commercial databases available to Hbrary users (111). 

Centralized systems reside at a central location and are accessed through a local area network (LAN), a wide area network (WAN), or a virtual private network (VPN). 

Computers. A certain number of personal computers are necessary for report generation and regulatory submission preparation. In addition, these may be useful for record keeping, depending on the type of stability information system that the company chooses to use. Alternatively, if the information system is intended to be accessible (read only) to many users, it may be more efficient to develop a local area network of mini-computers. The size of the database will help determine the nature of the software/hardware configuration used for this function. 

Any location that has a connection to the SCADA network is a target, especially unmanned or unguarded remote sites. Conduct a physical security survey and inventory access points at each facility that has a connection to the SCADA system. Identify and assess any source of information including remote telephone/ computer network/fiber optic cables that could be tapped radio and microwave links that are exploitable computer terminals that could be accessed and wireless local area network access points. Identify and eliminate single points of failure. The security of the site must be adequate to detect or prevent unauthorized access. Do not allow live network access points at remote, unguarded sites simply for convenience. 

WAP. The WAP provides the wireless data communication service. It usually consists of a housing (which is constructed from plastic or metal depending on the environment it will be used in) containing a circuit board, flash memory that holds software, one of two external ports to connect to existing wired networks, a wireless radio transmitter/receiver, and one or more antenna connections. Typically, the WAP requires a one-time user configuration to allow the device to interact with the local area network (LAN). This configuration is usually done via a Web-driven software application which is accessed via a computer. 

Firewalls may be a piece of hardware, a software program, or an appliance card that contains both. Advanced features that can be incorporated into firewalls allow for the tracking of attempts to log on to the local area network system. For example, a report of successful and unsuccessful log-on attempts may be generated for the computer specialist to analyze. For systems with mobile users, firewalls allow remote access to the private network by the use of secure log-on procedures... 

If your computer at work is on a local area network (LAN), you may already have access to an external connection. Almost all universities have permanent connections between their internal systems and the Internet. If you don t have access to an institutional connection, you have to obtain an access from an Internet service provider (ISP). For a full Internet connection, you must have software to make your computer use the Internet protocol, TCP/IP, and if your connection is through a modem this software will probably use PPP (point to point protocol). 

Nondedicated Servers These are assigned to provide one or more network services and local access. A nondedicated server is expected to be slightly more flexible in its day-to-day use than a dedicated server. Nondedicated servers can be used not only to direct network traffic and perform administrative actions, but often to serve as a front-end for the administrator to work with other applications or services. The nondedicated server is not really what... 

If your computer at work is on a local area network (LAN), you may already have access to an external connection. Almost all universities have permanent connections... 

The needs of the organization will determine the type of EDMS to be implemented. Systems can be local or, more commonly, distributed throughout the company to maximize the sharing of information and, hence, benefits. This distribution can be site wide or even intersite using local area networks (LANs) and/or wide area networks (WANs). The validation of such networks is covered in Chapter 12 of this book. Many systems are client-server based and may use a Web browser to provide read-only access into the system. The latter is changing with the introduction of Web-based interactive packages. Figure 10.1 provides an example of EDMS architecture for a multiuser distributed system. 

Connecting intranets at different geographical locations via the public Internet, results in extranets. If an organization is operating at different locations and wants to interconnect its TCP/IP-based LANs (intranets), it can use the inexpensive public Internet to establish secure channels between these intranets rather than build very expensive, large-scale, wide area private networks. This way, corporate-wide extranets can be formed, allowing internal users to access any part of this closed network as if it were a local area network. 

The data used in the experiment is KDD CUP 99 data sets. This data set provides 9 week s network connection data that gathered from on a simulation local area network. Each record in the data set has contains 41 features and 1 marking of kind. The record in the data set has been divided into 5 kinds, namely normal connection (Normal) denial of service (DoS), the unauthorized remote service to login (R2 L), the unauthorized access to the local super user s privilege, scanning and probing (Probing). 

One important application of spread spectrum communication systems is in the implementation of wireless local area networks (LANs). The attraction of such networks is obvious. A computer with access to a wireless LAN is completely untethered and a hard (wired) connection to a network is unnecessary. Wireless LANs are clearly advantageous in a situation in which computers are highly mobile (roaming), such as with laptop computers being moved from office to office or from an office to a conference room. Each computer carries its own RF transmitter and receiver, and such a system becomes very practical if licensing requirements can be avoided. 

Optical library systems fit well into a large computer-based environment, such as client-server systems, peer-to-peer local area networks, or mainframe-based systems. In such environments, there is a distinct storage hierarchy based on cost/access tradeoff of various types of data. This hierarchy is shown schematically in Fig. 14.22 asapyramid. The highest section of the pyramid contains the highest performance and highest cost type of memory. The most inexpensive (on a cost/megabyte) basis and lowest performance is that of tape. Optical libraries are an... 

As illustrated in Fig. 15.13, the pubHc telephony network consists ofusers with telephones, connected to a switching system over an access network. To allow connections between users that are not connected to the same switching system, the switching systems are aU connected to each other over the trunk network. Although access networks can be localized to the area surrounding the switching system, trunk networks... 

Calhoun, G. 1992. Wireless Access and the Local Telephone Network. Artech House, Norwood, MA. 

Some data files that are typically shared, especially in regionalized or multilocation companies, include customer hies, employee hies, and inventory hies. Distributed data access is even more of a concern when the users sharing the data are beyond the reach of a local area network and must share the data via wide area networking solutions. A good starting point for the network analyst might be to ask the question Has anyone done a comparison of the forms that are used in the various regional and branch offices to determine which data needs to be sent across the network ... 

Once the need for a network has been determined, the locations of terminals, servers, and information storage equipment must be established. Local area networks (LANs) and the worldwide web (WWW, or Internet) can link access points located in adjacent rooms or halfway around the world. However, it is critical that the network uses consistent computer and data transmittal protocols in order to provide uninterrupted, information handling in an efficient manner. For example, serial communication via an RS-232 port is relatively common, but too slow for most machine applications. Ethernet communication via transmission control protocol/Internet protocol (TCP/IP) is a preferred method because most equipment suppliers offer this network option. The TCP/IP method allows computers to share resources, no matter whether the operating system is for an Apple , a version of the Microsoft operating system for PCs, or the UNIX operating system. Also, the Semiconductor Equipment Communication Standard (SECS)/Generic Equipment Model (GEM) is widely used as the interface between the host computer and assembly machines. 

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