Building a Wide Area Network: Wireless Networking Essay

Introduction

Simulation is a standard method in the toolkit of modern engineers; before a piece of equipment, a car or a telecom network is built, it is tested in a computer model that reflects both the object that is tested as well as its surroundings. This project aims to describe the main challenges for radio network simulators in the context of a “beyond 3G” scenario. After an elaboration on the current practices around simulation in the design of radio systems and networks, the project concentrates on the characteristics of the “beyond 3G” scenario, and the challenges it poses to radio network simulators.

Interconnecting building a,b, &c

Technology to Be Used: Wireless Networking

Interconnecting 3 Departments each having a LAN1, LAN2, and LAN3

Building LAN1

All computers will run on Windows 2000 server and will have a wireless NIC with Outlook Express as the mail client software.

They will be required to run software applications such as Microsoft Office Professional (includes suite of applications including, Word, Excel, PowerPoint, and Access) and Great Plains Accounting Software (for personnel information, payroll, inventory, accounts payable, accounts receivables, quarterly and annual reports, and tax documentation). The two applications will be supplied to all the staff in this department to enable them to access the documents and information written in those applications.

However, only the data that is required to be used by all members in this Department is to be shared within the network.

You need to configure all computers as Clients for Microsoft Networks, and enable File and print sharing, and share all the peripheral devices such as printers required in the network. All these workstations will communicate through a wireless router. DHCP address or Static address can be used.

How to Create a Wireless Network

Computer networking is a great way to collaborate with other computer users in your home or office. While it is becoming increasingly easy for the basic computer user, it can still be a difficult, frustrating experience for many people.

Steps

• Decide on what type of network you wish to install. We will be covering how to install a wireless network including 2 desktop computers, 1 laptop, and a High Speed Internet (HSI) connection. If you wish to install a wired network, this manual is not for you.
• Purchase the following items for your Wireless Network:
• Wireless router (with switch)
  • PC wireless adapters for the desktop computers
  • Laptop wireless adapter for the wireless laptop
• Connect the wireless router to your High Speed Connection by turning off all units, including the computers. Simply use an Ethernet cable (which usually comes with your High Speed Internet Connection) to connect your HSI modem to the WAN port on your wireless router.
• Open your desktop computers and install the PC adapters, or purchase USB adapters that do not require you to open your computer. Also install any necessary software on each machine. Older operating systems need some drivers installed.
• Install the wireless PC card on your laptop, and install the included software. Then, shut down all computers.
• Turn on your new items in this order:
  • Your HSI modem (wait for all lights to return to normal).
  • Your New Wireless Router (wait for it to start up fully).
  • The computers. They should find the wireless router and connect to the network and the internet through the new router.

Tips

• To create a network that does not include internet access (or to ensure that your computers are networked), be sure to enable Print and File Sharing on all computers. This is done differently on the Macintosh, Linux and the Windows platform.
• For Windows XP and Vista, go to Start > Control Panel > Network Connections (click “Switch to Classic View” if you cannot see the Network Connections icon) > right-click on your Local Area Connection Ethernet adapter > Properties > check File and Printer Sharing for Microsoft Networks > Click “OK”
• For Macintosh OS X, click on the Apple menu on the Menu Bar and click on “System Preferences…”. Then, click on “Sharing”. Then you may select which service that you want to be shared on your wireless network. For further support, click on the Apple Support Page link for sharing on your wireless network. Apple Sharing Support

Warnings

• Turning on your equipment in the wrong order could cause your new setup to not work! Be sure to power on each item in the order. It does matter.
• Remember to set up your security settings to prevent unauthorized access to your network. WPA encryption is much more secure than WEP.
• Also remember to change the default passwords and usernames on your wireless router. Many wardrivers will travel around finding hotspots and then trying the default codes for that type of access point. This could result in you getting locked out of your router and having to manually reset your network.

Sources and Citations

• Wireless Networks related help.
• Detailed Wireless Network Setup Tutorial.
• 5 Ways to improve your Wireless Network.

Jack H, James Quirk, Papa G, Tom Viren, Rick Davis, Alfons Van Hees, Imperatrix, Joe Hamilton, Ben Rubenstein, Richard, Sondra C, TSS888, Jonathan E., Travis Derouin

For Email services, you will use Outlook Express to configure email accounts for all these workstations. Other peripherals like printers that need to be shared should be shared from the computer they are locally installed. If all the above tasks are performed perfectly, the LAN in the first Department should work properly providing all the services it’s meant for.

Building LAN2

This department consists of Business and Finance. This Department handles the accounting of the whole Company since these acts as the Headquarter. The flow of money in and out of the company is controlled here. However, this department will work under the supervision of the Administration Department hence the need for networking.

All computers will run on Windows 2000 server and will have a wireless NIC with Out Look Express as the mail client software.

They will also run applications be required to run software applications such as Microsoft Office Professional (includes suite of applications including, Word, Excel, PowerPoint, and Access). Since it’s a finance department, accounting software, in this case Great Plains Accounting Software (for personnel information, payroll, inventory, accounts payable, accounts receivables, quarterly and annual reports, and tax documentation), will be supplied to all the staff in this department. The two applications will also be supplied to the other staff in the other two departments to enable them to access the documents and information written in those applications.

However, only the data that is required to be used by all members in this Department is to be shared within the network.

Creating a LAN, you need to configure all as Clients for Microsoft networks, Enable File and print sharing. As for me, I would prefer use of static IP addresses instead of Dynamic IP addresses. All these workstations will communicate through a wireless switch. Outlook express is then configured for email which will work through the internet.

Other peripherals like printers that need to be shared should be shared from the computer they are locally installed. If all the above tasks are performed perfectly, the LAN in the first Department should work properly providing all the services it’s meant for.

Building LAN3

The last Department is for the Consultants. As the Department of Business and Finance, this department also works under the supervision of the Administration. However, it must also work together with the Business and Finance Department calling for the three departments to be networked. This LAN will have an equal look and performance like in the department of Administration.

However, this office in Building A being the headquarter and center of operation, it’s in this department (department of Consultants) that all networks will be controlled. The mailing server, Microsoft Exchange Server, Internet connection server, and the PBX systems for phone services, all mounted in a server cabinet. For the security of the company’s data, information, a secure room with proper heat and air conditioners is reserved to store the server cabinet. Only the authorized persons like the Systems administrator are around access to this server room.

Interconnecting the three LANs and Internet Connectivity

All the workstations in each department connect through a wireless router. The three wireless routers can communicate using a single wireless or wired router. This router is meant to work as a gateway server. This router will however be connected to a T-1 line for internet services.

T-1 line system enhances data and voice communication For the emails the mailing server, Microsoft Exchange server will also be connected to a gateway router.

A T1 line operates much like any other high-speed connection, and will connect to your LAN via a router just as a cable modem would. The only difference is that most of the time and special router is needed to connect via cable, and then you can take that into another router that will feed all of your machines in the network. With a T1, you don’t need a special router. You should be able to wire it right into your main router and have connectivity.

Depending on the kind of router that you currently have, if you have problems, it might only be because you need to use a crossover instead of a regular CAT 5 Ethernet cable, or you might need to plug it into a main port, uplink port, or LAN port (some routers, like the Linksys Wireless 802.11G, support all of these). (Marc Melvin 9/23/2004).

T1 carrier is one of the most popular leased line options for digital transmission that offers high speed internet connectivity at 1.544Mbits per second. A T1 line is comprised of 24 individual channels, each capable of transferring data at 64Kbits per second. With T1 Internet connection, you can have uninterrupted and reliable data transfer within seconds. In normal phone lines, voices are transmitted through copper wires as analog signals and you can transmit data at around 30 kilobits per second with your normal modem. A T1 Internet connection, on the other hand, is capable of carrying 24 digitized voice channels at the speed of 1.544 megabits per second.

A T1 carrier can carry 192,000 bytes of data per second – nearly sixty times more data than that of a normal residential modem. T1 Internet connection is capable of providing uninterrupted data transmission which you would not get if you use ordinary modems. If you want to transmit audio or visual data through your residential modem or through your phone service you have high risk of getting jammed since the speed is so slow. With a T1 service, you can eliminate this risk significantly.

Internet service by service providers converts all voice calls as analog rather than in digital format, which not only takes longer time but frustrates customers now that high speed is available. With a T1 line, you not only increase the speed of your data transmission but also save time for your valuable online work.

This article may be reproduced wholly or in part without written permission provided the byline, resource area, and any hyperlinks remain in order to give proper credit to the author.

Creating LAN in building B

When building a network, the type of technology matters though in most cases, it is possible to integrate all the available technologies. This building is very close to building A and therefore, it is possible to use cables to interconnect building A to building B.

To configure a wireless LAN in this building, we must put into consideration, the type of wireless connectivity we shall use due to distances and locations of offices within this building. By this I mean, the manager could be facing right side of the Receptionist, custodians on the right side of the Manager while the IT Support person and the consultants on the left side of the custodians. All these workers need to communicate and a proper network is required to facilitate this.

This LAN will be used to access internet from the gateway router in Building A, sending and receiving mails and uploading data from Access Databases using FTP. Software applications such as Microsoft Office Professional and Great Plains Accounting Software for accounting purposes.

All the workstations having each a wireless NIC and running on Microsoft Windows 2000 server operating system will communicate to a single wireless router. Workgroup names and the IP addresses will then be supplied to each one of them. Outlook express should also be configured as a POP3 client which should work through the internet to Building A’s Exchange email server.

Linking building b to building a

The purpose of linking the two LANs together is for email services, internet services and phones services. Email and internet services will be configured to work in the same way- emails will be accessible through the internet.

When connecting building B to building A, the best method I would prefer is a point-to-point connection. Being that there will also be a connection between building A and C, a point to multipoint connection is preferable such that an Omni will be mounted on building A which must be at the line of site with the two buildings. Then on buildings B and C, a Radial will be mounted to communicate to the Omni in building A.

Wireless Connection

Point-to-Point Microwave

Point-to-point microwave radio links have long been the technology of choice for cellular base station backhaul. With point-to-point, microwave radio and antenna is placed at the base station facing a similar radio and antenna at the Base Station Controller. These links carry one or more E1/T1 trunks, or their fractions. Point-to-point radios are available in a wide variety of radio frequencies, many of them dedicated worldwide to point-to-point applications. A large number of vendors supply a wide variety of microwave radio products at affordable, but somewhat high, prices.

Base Station Feeding Using Point-to-Multipoint

Point-to-multipoint technology is a highly attractive alternative for implementing mobile base station feeding solutions. Point-to-multipoint presents significant advantages over traditional backhaul methods such as leased lines and point-to-point wireless. In a point-to-multipoint architecture, a central site connects to multiple remote locations, sharing frequency spectrum and equipment. When used in a base station feeding application, several cellular Base Transceiver Stations are connected to a single radio and antenna at the Base Station Controller.

This concept allows for smooth network growth and expansion, and facilitates optimization as user patterns change – by allowing dynamic allocation of backhaul channels to any base station. When a base station requires more channels, additional bandwidth is simply allocated on the backhaul link by a network management command, limited only by the total capacity of the central site.

With point-to-multipoint there is no need to license individual links. Point-to-multipoint systems are licensed on a one-time basis. All additions and changes are covered by the original approval, and do not require regulator intervention.

Using a point-to-multipoint system requires a specific license from the regulator. The allocated frequency band is licensed for the exclusive use of the licensee. With the current telecom downturn, obtaining a point-to-multipoint license has become easier than ever. Once the operator owns this spectrum, the licensing issue is over. In cases where spectrum is not available to the mobile operator, it may be leased from the license holders, or backhaul services may be purchased from a broadband wireless access operator.

With point-to-multipoint, radio planning is performed only once for an entire area, using methods and tools similar to those used for cellular telephony. Adding base stations does not require additional radio planning, so long as backhaul capacity has been reserved for growth.

Installing base station backhaul in point-to-multipoint system is much simpler than in a point-to-point system. Once the point-to-multipoint central site is installed and radio planning is completed, connecting a new link becomes relatively an easy task. As the central site of the point-to-multipoint system covers a wide area, radio alignment at the mobile base station is easy and can be performed quickly, often by a single technician. With point-to-multipoint, the number of antennas at the Base Station Controller is greatly reduced.

Unlike the point-to-point solution, a single central site antenna serves multiple BTS sites. Typically, a maximum of four antennas will cover an entire area. This improvement not only decreases space requirements and wind-load on antenna masts, but also reduces the environmental and esthetic impact of backhaul deployment.

Point-to-multipoint systems offer significant cost savings over point-to-point. Since with point-to-multi-point, the central site radios and antennas are shared by multiple base station sites, the total cost of the system is reduced. In addition, due to mass production for Broadband Wireless Access applications, the cost of individual point-to-multipoint radios is lower than those of their point-to-point equivalents. All-in-all, point-to-multipoint systems can offer equipment cost savings of 50% or more, when compared to point-to-point systems. Moreover, point-to-multipoint systems also feature lower operating costs: There are fewer units to manage, and the remote terminals are managed as one system with the central site.

Unlike leased lines, a point-to-multipoint solution does not involve payment of an expensive monthly charge. It gives the mobile operator independence from its competitor, the fixed telephony service provider, and allows the cellular system to be deployed at its own pace – with no dependence on slow-moving, bureaucratic phone companies. Point-to-multipoint systems are orders of magnitude less expensive than installing private lines, which require digging and laying of copper or fiber infrastructure.

Cellular operators deploying point-to-multipoint systems for base station backhaul can, relatively easily, utilize the same infrastructure to provide Broadband Wireless Access services to business and residential users. Cellular Operators can thus capitalize on additional revenue sources by providing new services and applications using the same infrastructure and with minimal additional cost.

Alvarion WALKair Mobile Base Station Feeding Solutions

The WALKair Broadband Wireless Access System is a state-of-the-art point-to-multipoint radio system for broadband applications, which can provide an optimal solution for the mobile backhauling requirements. WALKair offers significant operational cost savings over leased lines and is much less expensive than point-to-point alternatives. Its modular architecture requires a small initial investment and features simple, fast and non-service-interrupting upgrades upon capacity growth or site addition. The WALKair system allows very high voice and data backhaul capacity, enabled by the high spectral efficiency of the radio interface. Spare capacity can also be used for Broadband Wireless Access applications, providing services to business customers.

RADWIN’s breakthrough WinLink™ 1000 Multi Point-to-Point architecture allows service providers and ISPs to provide multiple end-users with carrier-class services (TDM and/or Ethernet) and dedicated bandwidth from one hub location.

The Multi Point-to-Point concept builds on RADWIN’s unique Hub Site Synchronization (HSS) technology which synchronizes the transmission of collocated WinLink™ 1000 radios – thus eliminating mutual interference commonly experienced with collocated TDD radios. This allows for up to 16 WinLink™ 1000 units to be installed in the same site.

The Multi Point-to-Point architecture is ideal for a variety of target markets. Today, service providers and ISPs are using RADWIN’s Multi Point-to-Point architecture to provide their end-users with guaranteed dedicated bandwidth. Private networks such as enterprises are using the unique Multi Point-to-Point deployment concept to create high-capacity networks where each site enjoys its own dedicated connection.

The Multi Point-to-Point architecture allows service providers to benefit from a ‘pay as you grow’ concept, with fixed cost per connection and low risk in project development and cost. There is no need for a high initial investment in expensive hub sites such as the case with Point-to-Multipoint systems.

WinLink™ 1000 Multi Point-to-Point Benefits

• Deliver dedicated bandwidth per end-user
• Provide combination of TDM + Ethernet services
• Low entry costs; Scalability in network growth
• Easy planning – no need for radio planning
• No degradation in network performance as more users join the network
• Optimized for non-uniformly distributed high-end users

The Omni is connected to the gateway router in building A while the Radial will be connected to the router in building B.

Having connected building A and building B, all the employees in the two buildings should be able to have access to internet services, emails services and FTP services, all discussed below.

FTP services

The preferred server is configured to accept incoming FTP requests. The files that you want to make available should now be copied into the folder for access.

The File Transfer Protocol (FTP) contains a set of rules for transferring any type of file over the Internet between FTP servers and FTP clients.

Figure 1 illustrates how FTP works between the server and client. Both computers must be running TCP/IP over a network. The user makes FTP requests through a user interface (UI) which could be any FTP client software. The UI talks to the User Protocol Interpreter (UPI) that ‘talks’ to the Server Protocol Interpreter (SPI) through a default channel or port 21. PI initiates control and passes FTP commands through the connection.

As you can see by the diagram, the PIs not only talk to each other but also with the data transfer process (DTP) of each respective side. The DTP, in turn, is like a data pump. It receives a transfer request from PI and either sends or receives the data and passes it to the file system or storage device (hard drive). Port 20 is usually used to transfer data.

An FTP server is the most common type of information server and the most widely used method of Internet data storage and transport. FTP servers that hold large amounts of documents and files are considered archives. While most people access the Internet via Web browser, any file the user tries to download from the Web more than likely involves accessing an FTP server to get the desired file. A file sent from an FTP client to an FTP server is “uploaded” while a client “downloads” a file from an FTP server. To make an FTP server, you need a computer with FTP server software, TCP/IP connectivity and an Internet connection.

An FTP server can be accessed one of two ways: authenticated or anonymous users.

User FTP requires people to have an account on the server. They must enter a user ID and password to access the files. While logged in, all the files and information in the FTP directory structure are available to users, but they do not have the ability to execute arbitrary commands. This means that even though the user can access the files, they do not control the server remotely. A potential security problem with using FTP is that the password is sent as clear text. This means that people with programs called “sniffers” can detect and capture the user’s ID and password.

Anonymous FTP allows anyone on the Internet to access the server and download files. This type of server is desired when the host is not worried about security or wants users to have free access to the files available. Usually, a user ID or password is not required, but if it is the site provides the information for users.

You will notice that some FTP sites are faster or slower than others and that at times the transfer will have variable transfer rates. There are several reasons for these variations, mainly external to the server. For the most part, transfer rates are affected by:

1. The amount of bandwidth available between the server and the client site. A transfer can only be as fast as the available bandwidth.
2. The number of users logged on to the server and transferring files. The more users logged on and accessing files, the less bandwidth available for your transfer.
3. The amount of traffic on the Internet at the time of transfer. Even if you are the only one accessing a site, if the Internet is busy or slow, your transfer will also be slowed down.
4. How the data is routed across the Internet. Since packets are routed individually, they may not be sent across the same route. Remember, packets are routed through the fastest way the router can find at the time it receives the packet. This means that one packet could be routed to you in two hops while the next one may be routed three hops.

While FTP started out on a UNIX platform, it has been adapted to run on other operating systems. Today, most FTP servers are run on UNIX, Novell or Microsoft NT servers. While these operating systems include their own FTP servers, various independent FTP server packages are also available.

Reynolds, Joyce, and Jon Postel, “Assigned Numbers”, RFC 943, ISI, April 1985.

Internet Connection

Having created a LAN in this building (building B), and connected building B to building A, it is now possible to configure an internet connection. A point to multipoint connection is used.

This can be achieved by configuring the IP address to the router in building B and registering that address to the gateway router in building A. All the workstations connecting to this router should be able to have internet service.

Creating LANs in building C

This building is the third premises for this company. The number of workers in this building is similar to the number of workers in building B. However, two independent LANs exist, all running on Novel Netware.

The LAN architecture used is similar to the one in building Band A though Novel Netware is used. Here one machine is configured with Novell Netware Server while the workstations will run on Novell Client Software. The two servers will then connect to a router which will be used when linking buildings A and C.

Novell NetWare

NetWare is a network operating system developed by Novell, Inc. It initially used cooperative multitasking to run various services on a PC, and the network protocols were based on the archetypal Xerox XNS stack.

NetWare Connect Services (NCS) Overview

NetWare Connect Services (NCS) is the networking technology infrastructure Novell is providing to telecommunications carriers. NCS offers full support for Novell NetWare applications. The NCS environment is a shared, multiprotocol networking platform that routes both IPX and IP traffic among attached networks. Customers connect to an NCS-enabled network via dedicated or dial-up connections. NCS offers a variety of opportunities to developers, including the ability to leverage Novell Directory Services’ security features, as well as the capability of using single sign-on for applications.

Introduction

NetWare Connect Services (NCS ) is part of the technology infrastructure that Novell is developing for data communication carriers to create a secure business-to-business information network, which extends current networks beyond their existing boundaries. The security, ease-of-use and connectivity of NCS, in conjunction with the quality, performance and reliability of carrier networks, create an open, highly functional data communications environment for businesses. NCS is an IP and IPX internetwork designed to complement other information networks.

NCS thus expands the information superhighway concept for inter-and intra-company communication and operation. It will allow businesses to reduce the expense of building and operating their own private internetworks.

A Public Network for Global Business

As the world moves ever faster toward a global economy, people and businesses need the tools and infrastructure that can ensure global transactions take place securely and reliably. There is no public network available today that has both the security and reliability of a NetWare network and the reach of the telephone infrastructure.

The net effect of NCS and the partnership between Novell and others will be the creation of a global LAN a worldwide network that provides all of the benefits of the NetWare 4.1 local area network, including high performance and ease of use. Businesses everywhere will obtain another notable benefit: they won’t be burdened with building, maintaining and administering complex wide-area networks, servers or applications. And they won’t have to replace existing operating systems.

Market Availability

NCS provides a platform for global internetworking consisting of multiple NCS-enabled networks with services provided by affiliated telecommunications carriers.

Novell’s first alliance was with AT&T. We have been working very closely together to define the standards of this first public version of NCS, AT&T NetWare Connect Service that is now available from AT&T.

Novell has also announced partnerships with Deutsche Telekom (Germany), NTT (Japan), Telstra (Australia), and Unisource (northern Europe) who each intend to offer their own NCS network service to business customers. These communications companies will work together to interconnect their networks, under the umbrella of NCS, allowing customers to easily access users and information located on any of the affiliate networks and provide developers an open and robust development platform with full interoperability.

In addition, Novell, AT&T, telecommunications carriers and other technology companies have joined in forming the Multimedia Services Affiliates Forum (MSAF) to further define this technology.

Developing Applications for NCS

Below are just a few of the many benefits you will receive when developing an application to run on NCS.

• Infrastructure to deliver genuine inter-and intra- enterprise applications.
• Familiar with open platforms for new and advanced applications and services.
• Leveraging Novell’s directory and security technology so that the developer can concentrate on unique application requirements rather than spending time reinventing technologies that Novell has already developed.
• Existing NetWare-based applications can be extended to NCS with minimal effort.
• Access to the global directory using standard Novell APIs.

Opportunities for Developers

Novell places tremendous value on the business relationships it maintains with its partners. You bring expanding market acceptance and brand momentum to Novell and its products. You also benefit by being aligned with the leading network operating system vendor in the industry. With NCS, you are provided even a greater opportunity. An opportunity to be aligned with the leading telecommunications carriers around the world, to broaden your applications’ reach, and to enter new markets you may never have been able to.

With Novell Directory Services, the Directory of choice by these worldwide carriers, a wide array of offerings are available to you for adding value to your applications. You can leverage the unprecedented security mechanisms within Novell Directory Services for user authentication, eliminating the need for you to develop your own security mechanisms. This also provides the ability for single sign-on to your applications-end users will no longer have the annoying task of re-entering username and password to use your application; it is handled transparently through NDS security.

The NCS global Novell Directory Services tree, has base objects and existing user information that your application can take advantage of, saving you time in building another address book.

There are unlimited applications and services that can be developed or enhanced to run on NCS. If it runs on an enterprise network, it should run unmodified on NCS. The rich development platform available with NCS provides you the ability to easily add value to your application, saving you development time and money.

The NCS Architecture

NCS is the networking technology infrastructure Novell is providing to telecommunications carriers. It is being developed with proven Novell technology. NCS provides full support for Novell NetWare applications. The primary features of NCS-enabled networks are security, reliability, ease of use, predictable performance, and cost effectiveness.

The strength of the service comes from its combination of the Novell local area network technology and the telecommunications carriers’ expertise in providing high availability wide area networking. The synergistic effect: a rich networking environment for application developers as well as end-users.

The NCS environment is a shared, multiprotocol networking platform that routes both IPX and IP traffic among attached networks. Customers connect to an NCS-enabled network via dedicated or dial-up connections. For seamless NetWare internetworking, NCS-enabled networks support mechanisms that provide users with information on NetWare services and resources available to them throughout the entire network. These resources include customers’ own corporate resources as well as other value-added applications and services that are available to customers based on a carrier’s implementation of their service.

Novell Technologies

NCS provides a fertile applications development environment, all with the tools you are used to. NCS is based on the following Novell products:

• NetWare 4 (supporting NetWare 2.x and 3.x)
• NetWare Directory and Security Services
• NetWare Link Services Protocol (NLSP) and IPXWAN
• NetWare Connect
• NetWare Multiprotocol Router
• NetWare Mobile
• LAN Workplace
• ManageWise

Infrastructure Protocols and Routing

NCS supports IPX and IP protocols. The carrier backbone uses NetWare Link Services Protocol (NLSP) routing. Routing Information Protocol (RIP), Novell Directory Services (NDS), static routes and services, and IPX default routes are supported for IPX customers. For IP customers, RIP, static routes, and IP default routes are supported. NCS accepts RIP or NLSP from customer networks; however, SAP is not allowed inside the carrier networks. Bindery Gatekeepers in the carrier networks are available to provide connectivity to NetWare 2.x and 3.x resources.

All network numbers advertised to an NCS-enabled network must be registered and all networks advertised as reachable to an NCS network are reachable by any directly connected customer. However, only routes to core services and the default route are advertised to customers.

Network Access

Users can access NCS through dedicated or dial-up connections. Dedicated access is currently available through Frame Relay. Dial-up access is available through an asynchronous connection or ISDN.

Client Software

A client can access NCS with three different options. An end-user could use:

• NCS client software that is offered by the carrier
• The standard NetWare client for LAN users or
• Third-party client software/third-party TCP/IP stacks.

Below are the components of the NCS client software provided by the carriers.

Component

Function

Standard NetWare Client

VLMsproviding basic NetWare connectivity

Dialer

Dialingand connecting to remote services (including NCS)

IPX and IP Protocol Stacks

IPXfor connectivity with NetWare LANs and TCP/IP for Internet access

WinSock 1.1

Standardinterface to TCP/IP stacks

NetWareEnd-User Utilities

Login,drive mappings, printing, and other network functions

InternetUtilities

NetScapeNavigator 1.22, Rapid Filer (FTP) and Host Presenter (Telnet)

BinderyGatekeeper Navigator

Access to NetWare 2.x and 3.x services

This component list was accurate at time of printing, but the components provided by specific carriers may vary, and this list may be updated periodically.

Network Directory

Carriers implementing NCS are using Novell’s Novell Directory Services as the network Directory. Novell Directory Services is providing the key security mechanisms for the authentication and certification of users accessing the carrier networks. The Directory is organized geographically based on the structure developed by the North American Directory Forum (NADF). Using this structure, companies are placed at a level in the Directory tree that is appropriate to their business reach.

For example, companies who do business nationally can appear directly under the country name, while smaller companies who do business regionally can appear under a state, province or locality name. Customers of NCS networks have the option of taking part or all of their directory available to their customers, suppliers and/or partners.

Added Value Services

There will be value-added services that will be made available to customers of an NCS network that depend upon the offering of the carrier. Such type of services includes access to information networks such as CompuServe and access to other services/applications that may be hosted by a carrier or by another company connected to NCS.

Providing a Service over NCS

If you have an application that you would like to make generally available over an NCS network to the network subscribers, that opportunity is available to you. In most cases, all that is required is that you subscribe to a carrier’s service and establish a connection to the network.

There are three ways that you can deliver a service over NCS:

1. Any application that runs on NetWare can be used with NCS. For example, if you have remote users that dial in from remote sites to access your network, you can use an NCS network as the conduit for that communication rather than a toll phone line.
2. You can set up a dedicated connection to your LAN to NCS and provide the service through the network. For example, if you have or are planning an online service, you can simply connect to NCS and immediately have wide-area connectivity for remote clients.
3. You can offer a service on NCS, but have the system actually hosted by the telecommunications carrier or some other third party.

Below is a diagram that depicts the components that comprise an NCS network as discussed above.

Process for Establishing a Connection to NCS

Below are examples of how a subscriber to an NCS network would connect to the carrier service and access resources.

Dial-Up Connection. John is a telecommuter working from home 3-4 days a week and he accesses his company network via NCS. His company, World Electronics has a dedicated frame relay connection to NCS. To connect through NCS,

1. John, loads his NCS client software.
2. He then clicks on the dialer function to connect to his company LAN; the dialer can be preconfigured with phone numbers depending on where John is dialing in from, or John can enter the phone number to dial on the fly.
3. Once this takes place, John is connected to a NetWare Connect dial-in server in the carrier network. This is where the first level of authentication takes place. Through NetWare Connect, John is authenticated via PPP.
4. If this is successful, John can then log in to the NCS global tree and/or directly to World Electronics corporate tree. During PPP authentication, John’s home server information within World Electronics is passed to the client via NetWare Connect.
5. Once this second level of authentication takes place and is successful, John is connected to his company LAN and has access to all his usual resources.

Based on John’s access control rights he may have access to other resources available on the NCS network that are outside his corporate network. John can also browse the Internet over the NCS network using any Internet browser.

Dedicated Connection. ABC Distributors has a dedicated connection to an NCS network so that their customers and remote sales force can always access their Sales and Inventory system to order products.

• ABC Distributors’ customers may access to ABCDistributors’ Sales and Inventory system at any time through the dedicated connections from their own LANs to NCS.
• Dial-in clients may access ABC from any dial-in connection to NCS.

Linking Building C to Building A

The connection between building A and building B is similar to that which should be used when connecting building C to building A. The two servers for the two LANs in building C connects to a single router which will be used to connect to the wireless systems for the purpose of the wireless connection between the two buildings (building A and C).A point to multipoint technology discussed earlier should be used. Internet connectivity, email services and FTP services will also be meant to work similarly. This new branch has been using dial-up internet access and email services through AOL. However, the configuration for internet and email services will be done as it was done in building C.

Phone Services for the Three Buildings

PBX System

Phone services will be essential for communication between the company and their clients and also among the company workers.

Initially, building C has been using a normal telephone service from the Local Telephone Company. But a PBX system will now be installed in each of the buildings ensuring effectiveness of Voice Mail, Call Waiting and Call Forwarding.

Standard PBX

PBX Definition: Premise-based definition of PBX

The term PBX stands for Private Branch eXchange. A PBX, sometimes known as a phone switch or phone switching device, is a device that connects office telephones in a business with the public telephone network. The initial central functions of a PBX were to route incoming calls to the appropriate extension in an office, and to share phone lines between extensions. Over time, many functions have been added, such as automated greetings for callers using recorded messages, dialing menus, connections to voicemail, automatic call distribution (ACD), teleconferencing, and more.

Today, PBX systems are expected to handle a wide variety of duties beyond simple connection to the public phone system. The range of features offered by a PBX varies, usually in proportion with the price of the equipment. Some of the main functions:

• Present a single business number that gives access to all company employees and departments
• Answer calls with a custom business greeting
• Offer a menu of options for directing the call, such as connecting to a specific extension or to a department
• Provide a directory of employee extensions accessible by inputting digits corresponding to employee first or last names
• Evenly distribute calls to a department among available employees through Automatic Call Distribution (ACD)
• Place callers on hold when they are waiting for an available department employee
• Play music or custom messages whenever callers are waiting on hold
• Take voice messages for any employee extension, for a department, or for the company in general
• Allow transfer of calls between extensions
• Conference multiple incoming calls with employee extensions
• Provide detailed call records and real-time system management

Of course, not every one of these features is available in every PBX system. The hardest feature to provide has been Automatic Call Distribution (ACD), and usually vendors charge a premium for products that include this feature. Other features that often get left out include integrated voice messaging, conference bridging for conferencing multiple outside calls, and detailed real-time system monitoring. Many times some of these features are not part of the base PBX system but can be purchased through add-on system modules.

Diagram & Operation

In a typical office environment, the PBX system connects multiple incoming phone lines to multiple telephone extensions. Basic PBX switches do little more than cross-connect these lines. As system price rises, functions are added. Some added features can be provided through software and/or firmware upgrades inside the basic hardware. For other features add-on modules are required.

Usually, the PBX device is a piece of hardware that hangs on a wall or mounts in a rack. Some type of patch panel is included that allows connection to internal and external telephone wires. Sometimes, PBX functionality is provided through software. In this type of system, a personal computer controls system operation and adapter cards and add-on modules provide connectivity.

Operation is fairly straightforward. Callers that want to reach someone in the company place their calls from any type of telephone. The call is routed through the Public Switched Telephone Network (PSTN) to company-specific lines leased on a monthly basis from a telephone company. The PBX system answers the call with a recorded greeting, plays a menu of connection options to the caller, and then routes the call to the appropriate employee extension or to a holding queue (ACD queue or hunt group) for a department, such as sales or support. In installations where the company wants calls answered by a person instead of a machine, the calls are first routed to an operator or receptionist who then forwards the call to the proper extension or department.

Calls transferred to an extension will ring at a particular phone, usually a desk phone somewhere in the office. If the extension owner picks up the phone the call is connected. If not, the call is usually transferred to voice mail.

When callers know what department they want but don’t have the name or extension number for a particular individual, they usually have the option to be sent to a holding queue to wait for the next available agent (employee) to take the call.

Many low-end systems do not offer any type of holding queue, and callers must know who they want to speak with before they call. Other low-end systems send callers to a “hunt group” – a list of phone numbers to try and find someone available. Hunt groups usually have the drawback that every extension number must be tried, in the same order each time, in an attempt to find an employee that can take the call. In such cases, the first extension on the hunt list usually gets swamped with calls while other extensions are used only when there is a heavy load. Another disadvantage of hunt groups is the time it takes to try each extension to find one that isn’t busy and has someone ready to pick up the phone.

Higher-end PBX systems employ a variety of techniques to assure that calls to a holding queue are answered more efficiently. The most prevalent approach is through the use of Automatic Call Distribution (ACD) queues.

A system with ACD queuing keeps track of which employees are already taking calls and how long it has been since each person finished prior calls. Incoming calls are put into the queue waiting for the next available employee and then routed automatically to the employee that has been off the phone the longest. ACD queuing evenly distributes calls to employees while ensuring a minimum wait time for each caller on hold. The ACD queue feature can add considerably to the cost of the PBX system but is often a major factor in customer/caller satisfaction. Serious businesses usually need the advantages of true ACD queuing.

VoIP PBX Solutions

Business communications have always been a challenging arena for management; subject to cost, function, reliability, and other pressures and concerns. The emergence of VoIP technology, and specific application to PBX systems via IP-based protocols, has provided an enormous opportunity for companies to reap many benefits.

Many companies today have multiple office locations around the country or around the world. Currently, each office uses its own PBX system and inter-office phone calls are routed through the PSTN and charged long-distance and international rates by carriers. Most companies also employ workers on a part-time basis who work from their homes. Those workers get reimbursed for telecommunication expenses they incur while performing their duties. It just makes business sense for companies to explore alternatives to consolidate their telecommunication systems and reduce costs.

The answer: A Voice-over-IP enabled PBX system in a virtual office model

Voice-over-IP (VoIP) is a fairly new technology for transporting voice calls over the Internet which allows users to realize substantial cost savings on long-distance and international calls. Besides cost-effectiveness, VoIP enabled PBX systems (or IP PBX) offer easy integration with existing telecommunications systems and are characterized with low operating costs as their upgrade is done through software updates rather than more expensive hardware replacement. Additionally, the technology simplifies the communication infrastructure (no need for separate voice and data cables) while offering high scalability.

Virtual Office models are used by companies that want to consolidate their communications, reduce costs and achieve more cohesive corporate images. To implement the model, a company has to install a single IP PBX system in its headquarters and distribute to employees IP phones or regular phones with VoIP adapters. Employees can make intra-office and inter-office phone calls by dialing PBX extensions. Such calls are routed through the Internet and are practically free. Company customers, on the other side, can dial a single inbound number plus extensions in order to reach the company’s employees. The latter receive the calls on their IP/Regular Phones at any location in the world with Internet connectivity.

Here’s an overview of what to look for when making the business case for investment in VoIP technology for a VoIP PBX solution:

• Eliminate or reduce intra-office toll charges
• Avoiding service and support contracts on existing PBX hardware
• Eliminate the need for ongoing Centrex services and charges
• Reduce expansion costs via lower costs for adds, moves and changes; lower user hardware costs
• Reduce the ongoing costs for separate voice messaging systems
• Provide productivity benefits for remote and traveling workers who can be empowered with the same integrated capabilities as office workers
• Reduce user training and learning on phone and messaging systems
• Cost-effectively implement unified messaging
• Improve security
• Reduce systems downtime and improve performance

How Does The Solution Work?

Inter/Intra office calls

Caller A, who is located in the corporate headquarters, wants to make a call to Caller B, who is located in the corporate headquarters or in any of the company’s offices worldwide.

Caller A picks up his VoIP device (IP phone, phone with adapter or softphone) and dials Caller B’s extension.

The VoIP PBX server searches its internal database and obtains call routing information about Caller B The VoIP PBX server routes the call to Caller B’s VoIP device.

If the destination number is unreachable, the system forwards the call to Caller B’s voicemail.

As soon as Caller B picks up his VoIP device the conversation starts.

During the conversation Caller A’s VoIP device convert voice to digital packets and send them to Caller B’s VoIP device and vice versa.

Both A and B can use traditional PBX functionality, like call on hold, caller ID, call forward, etc. Calls are free

Outbound calls

Caller A, who is located in the corporate headquarters, wants to make a call

to Caller B, who is a company customer.

Caller A picks up his VoIP device (IP phone, phone with adapter, or softphone) and dials the customer’s number.

The VoIP PBX server searches its internal database and obtains call routing information about the VoIP carrier, who should terminate calls to Caller B’s area code.

The call is routed to the VoIP carrier.

The VoIP carrier terminates the call to Caller’s B number over the PSTN.

During conversation, Caller A can use traditional PBX functionality, like call on hold, caller ID, call forward, etc.

Calls are charged on time basis at pre-negotiated rates with the VoIP carrier

Inbound calls

Caller A, who is a company customer, wants to make a call to Caller B, who is a company employee.

Caller A picks up his phone and dials the company’s central access number.

The VoIP PBX server prompts the caller to enter an extension.

Caller A dials Caller B’s extension.

The VoIP PBX server searches its internal database and obtains call routing information about Caller B.

The VoIP PBX server routes the call to Caller B’s VoIP device.

During conversation, Caller B can use traditional PBX functionality, like call on hold, caller ID, call forward, etc.

Calls are either free if the company uses a local access number or charged on a time basis if the company uses a toll-free one.

Voice over IP (VoIP) technologies carry great promise to reduce telecommunication and networking total cost of ownership while empowering businesses with new capabilities and agility. When making your decision on deploying a Virtual Office VoIP PBX solution consider the strategic and tangible benefits as well as the costs and risks outlined above. If it all seems too overwhelming just let Firepair Consulting design and implement a system that’s right for you and your company.

Recommended Reading for People Who Are New to the Field

• F. Baker, “An outsider’s view of MANET,” Internet Engineering Task Force document (text file). 2002.
• C. Barrett et al., “Characterizing the Interaction Between Routing and MAC Protocols in Ad-hoc Networks,” Proc. MobiHoc 2002 , pp. 92-103.
• J. Broch et al., “A Performance Comparison of Multi-Hop Wireless Ad Hoc Network Routing Protocols,” Proc. Mobicom ’98.
• D. Cavin et al., “On the accuracy of MANET simulators,” Proc. ACM Workshop on Princ. Mobile Computing (POMC’02). 2002, pp. 38-43. online.
• K.-W. Chin, et al., “Implementation Experience with MANET Routing Protocols,” ACM SIGCOMM Computer Communications Review. 2002, pp. 49-59.
• M. S. Corson et al., “Internet-Based Mobile Ad Hoc Networking,” IEEE Internet Computing, 1999, pp. 63-70.
• C. Elliott and B. Heile, “Self-Organizing, Self-Healing Wireless Networks,” Proc. 2000 IEEE Int’l Conf. on Personal Wireless Comm., pp. 355-362.
• L. M. Feeney, “A Taxonomy for Routing Protocols in Mobile Ad Hoc Networks,” Swedish Institute of Computer Science Technical Report T99/07, 1999.
• M. Frodigh, et al, “Wireless Ad Hoc Networking: The Art of Networking without a Network,” Ericsson Review, No. 4, 2000.
• Z. J. Haas, et al., eds., Special Issue on Wireless Ad Hoc Networks, IEEE J. on Selected Areas in Communications, Vol. 17, No. 8 (1999).
• J. Heidemann et al., “Effects of Detail in Wireless Simulation,” SCS Communication Networks and Distributed Modeling and Simulation Conference, 2000.
• P. Johansson et al., “Scenario-based Performance Analysis of Routing Protocols for Mobile Ad-hoc Networks,” Proc. Mobicom ’99, pp. 195-206.
• D. K. Kim, “A New Mobile Environment: Mobile Ad Hoc Networks (MANET),” IEEE Vehic. Tech. Soc. News, 2003, pp. 29-35.
• D. Kotz, et al., “Experimental Evaluation of Wireless Simulation Assumptions,” Dartmouth College Computer Science Technical Report TR2004-507, 2004.
• S. Kurkowski, et al., “MANET Simulation Studies: The Incredibles,” ACM SIGMOBILE Mobile Computing and Communication Review, Vol. 9, Issue 4 (2005), pp. 50-61. Citation page
• T. Larsson and N. Hedman, “Routing Protocols in Wireless Ad-hoc Networks–A Simulation Study,” master’s thesis at Lulea University of Technology, Stockholm, 1998.
• P. E. McKenney and P. E. Bausbacher, “Physical- and Link-Layer Modeling of Packet Radio Network Performance,” IEEE J. on Selected Areas in Comm., Vol. 9, pp. 59-64 (1991).
• Tao Lin, et al., “A Framework for Mobile Ad Hoc Routing Protocols,” Proc. IEEE 2003 Wireless Comm. and Networking Conference (WCNC 2003).
• N. Patwari, et al., “The Importance of the Multipoint-to-Multipoint Indoor Radio Channel in Ad Hoc Networks” [measurements at 925 MHz] Proc. IEEE WCNC 2002.
• K. Pawlikowski et al., “On Credibility of Simulation Studies of Telecommunication Networks,” IEEE Communications Magazine, 2002, pp. 132-139.
• C. E. Perkins, Ad Hoc Networking. New York: Addison-Wesley, 2001.
• S. Ramanathan and M. Steenstrup, “A survey of routing techniques for mobile communications networks,” Baltzer/ACM Mobile Networks and Applications, vol. 1 (1996), pp. 89-104.
• E. M. Royer and C.-K. Toh, “A Review of Current Routing Protocols for Ad Hoc Mobile Wireless Networks,” IEEE Personal Communications, 1999, pp. 46-55.

Conclusion

Besides the public (mobile) operators, the introduction of dedicated networks has spawned private network operators. Examples are the GSM-rail, TETRA, and WLAN hot spot operators, and military networks. Most of these operators ask for turn-key solutions from their vendors, hence the need for simulations is more or less absent. The defense departments are an exception to this rule. Since they want to be sure that their networks can be operated in extreme conditions, they run extensive network simulations to prove this [6].

Like with the public mobile operators, testing equipment under realistic and extreme conditions is the major perspective shift compared to standard simulations. This perspective adds the following conclusion to the previous ones:

• The use of parallel computing for radio network simulation is still in its infancy, especially when compared to other industries.