LDDS WorldCom | Vendor Implementations

The ubiquity and user-friendliness of the World Wide Web is prompting long distance carriers to reevaluate how they give users a view into their networks. Traditionally, obtaining network-performance data has been more difficult and more expensive than most customers are willing to buy into. Moving this function to the Web facilitates the acquisition of real-time performance data using the familiar browser interface. Not only are more network management tools being equipped with hooks into the World Wide Web, but some expensive management platforms are being discontinued because they do not compete well against Web-based tools that do. Among the long distance carriers that offer Web-based management tools is LDDS WorldCom.

LDDS WorldCom, the fourth largest long distance carrier in the United States, offers its customers a Web-based Network Management System (Fig. 1) that is accessed through a client equipped with a standard Web browser. With the browser, users can monitor the performance of their data and voice WANs. The system gives network administrators their choice of hour-by-hour and day-by-day statistics on frame relay, dedicated access, and toll-free circuits. For example, on a near real-time basis, frame relay users can see hourly and daily reports on the percentage of frames marked discard-eligible due to bursting above the committed information rate (CIR). Users can also compare CIRs to actual traffic load to help determine when port expansion is necessary.

Figure 1: Architecture of the LDDS WorldCom Web-based management capability, which gives users reports on their portion of the network.

The reporting service makes it simpler for managers and administrators to get into the network to obtain performance-related information, without requiring them to buy additional hardware and software compatible with their provider's network monitoring capabilities. Customers can use Web NMS to obtain usage statistics, such as: originating number, number of no-answers, and average call duration for customer toll-free numbers; trunk group activity levels on dedicated access lines; and port/PVC usage on frame relay service. In near-real time, Frame Relay customers can use Web NMS to:

§  Open a window into the network when considering a change or upgrade to their existing frame relay facilities

§  Track how much of their traffic is "bursting" above the committed information rate (CIR) to discard-eligible status

With regard to toll-free 800 or 888 numbers, the Web NMS toll-free application enables call center managers to do such things as determine on an hourly basis how many calls are being answered or dropped in queue for each telephone number. In near-real time, toll-free customers can use Web NMS to:

§  Monitor usage volumes on individual facilities to best distribute calls among multiple answering locations

§  Ensure that all calls are getting through

§  Adjust staffing based on traffic load reports

§  Track response to specific toll-free numbers used in advertising campaigns and on product packaging

In near-real time, Dedicated Access Line (DAL) customers can use Web NMS to:

§  View trunk group activity levels reports

§  Based on trunk group reports, use conventional means to best allocate available bandwidth between multiple services—for example, between outbound and inbound trunk groups

§  Based on trunk group reports, use spare capacity for point-to-point data services

To use the Web NMS, users actually go into WorldCom's password-protected corporate intranet. An additional level of security is provided by partitioning the servers on a customer-by-customer basis. Hyperlinks enable Web NMS users to click on individual physical or virtual circuits, check the traffic load through specific frame relay ports, or switch among hourly, daily, and historical summaries. The Web NMS screens also include online help and customer feedback links.

SNMP Research | Vendor Implementations

SNMP Research International Inc. offers a unique product that maps HTML constructs and SNMP data, supporting a standards-based transition to Web-based management. For management applications, DR-Web reduces coding effort as well as memory requirements. For developers and end-users, DR-Web preserves investments in SNMP by ensuring consistent data naming with more than 5000 standard MIB objects specified in over 60 RFCs.

The DR-Web Extensible Agent is one of three products in the DR-Web family of Web-based management tools from SNMP Research. The architecture of DR-Web provides operators with easy access to management information from any Web browser while preserving the standards-based format of management data required for programmatic manipulation by software applications. DR-Web's primary differentiator from other Web-based management solutions is the level at which SNMP/Web integration takes place in the agent/management architecture (Fig. 1).

Figure 1: Architecture of DR-Web Extensible Agent.

From any popular browser, operators can request SNMP management information from DR-Web-enabled applications, systems, or devices by making an HTTP request in the form of an Uniform Resource Locator (URL), such as:

http://my.host.machine:280/subtree/

where the host is the host name or address for the computer running DR-Web, and subtree specifies the starting point for browsing the SNMP MIB. Port 280 is the proposed port for Web-based management, pending approval by the IETF.

Upon receiving the HTTP request, DR-Web retrieves information from the Subagent and converts SNMP MIB data into HTML pages. The operator can easily create customized pages using point-and-click operations. For example, network administrators may want to create a page called "routerstatus" which contains only those MIB variables of interest to them. Operators can retrieve this customized page again and again without respecifying the variable grouping.

The DR-Web Extensible Agent is actually an enhancement to SNMP Research's EMANATE Master Agent/Subagent system. The EMANATE Master Agent is extended to support an HTTP interface as well as the existing SNMP interface to the event queueing subsystem. DR-Web converts HTTP requests and SNMP requests to EMANATE events, and dispatches them to the appropriate Subagents. Because this modular architecture requires no changes below the event queuing subsystem, all customer investment in EMANATE-based SNMP subagents is preserved. The layering approach also allows for future support of the HyperMedia Management Protocol (discussed later) as well as other new protocols without requiring changes to the Master Agent/Subagent relationship.

The DR-Web Extensible Agent meets the needs of those seeking applications, systems, or device management solutions that are both standards-based and accessible via Web browsers. Using the automatic code-generating facilities provided by SNMP Research's Subagent Development Kits, users can generate Subagents for monitoring critical application processes. Checking the status of an application or changing its priority can then be accomplished at the nearest available Web browser.

Hewlett-Packard & IBM | Vendor Implementations

Hewlett-Packard

Web-based management capabilities first appeared in enterprise management platforms, but have since migrated to LAN management platforms. Hewlett-Packard, which offers Web interfaces to its enterprise-oriented HP OpenView Network Node Manager, has extended that capability to the LAN-oriented Professional Suite, a comprehensive software solution that allows customers in small to midsize networked environments to manage virtually all elements of a PC LAN. Included with HP OpenView Professional Suite is Microsoft's Web browser, Internet Explorer.

This enhanced version of HP OpenView Professional Suite can automatically discover Web devices. It can also provide a menu that lets the administrator launch a Web browser to display the management page of any device that can be managed via Web technology. With the Web interface, a network administrator is able to access Web-based LAN management information from any location, such as a remote server site or a home computer.

HP OpenView Professional Suite combines the power of a central management console, including automatic discovery and map generation, with the ease of using the Web to manage devices. OpenView provides direct access from the map to the management page of devices that can be managed through any standard browser, including Netscape Navigator. OpenView accomplishes this by automatically discovering these devices and providing menu items that launch a Web browser with the appropriate page displayed.

Among the hardware that can be managed by the Professional Suite—that also can be managed via the Web—include HP PowerWise uninterruptible power supplies and HP LaserJet printers.

IBM

HP's main competitor IBM also offers systems management capabilities through the Web. Since early 1996, IBM has been giving administrators the means to monitor PC and server performance via the Internet. Starting with version 4.0 of PC SystemView (formerly known as NetFinity), any machine with a Web browser can be turned into a PC SystemView management console. A typed-in code provides access via the Internet to a server running PC SystemView Manager software containing Web-enablement code. Once logged on to a network, an administrator can use PC SystemView to perform such tasks as manage desktop or server performance, configurations, problems, and security.

Frontier Software Development | Vendor Implementations

Frontier Software Development offers WebCast, a tool that provides access to the reporting capabilities of Frontier's NETscout Manager through common Web browsers. With WebCast, network managers can see end-to-end network reports through all seven layers of traffic on any topology, including Ethernet, Token Ring, Fast Ethernet, Switched LAN, VLAN, WAN, Frame Relay, FDDI, and CDDI.

WebCast automatically converts NETscout Manager traffic reports into Web pages that can be read quickly and easily by authorized users throughout a distributed computing network. This makes network data, traps, and Java-enhanced alarms accessible through an organization's intranet at very low cost.

WebCast makes all this network data available over the Web through its EnterpriseRMON, which is a superset of RMON1 and RMON2. EnterpriseRMON extends standard RMON functions by adding client/server application traffic reports, and improves enterprise traffic management and system-level troubleshooting.

In addition to its detailed reporting capability, WebCast gives network administrators location-independent management capabilities. Administrators can use WebCast to configure probes and agents on a network or edit agent configurations through a Web browser. For example, managers can use WebCast to view utilization reports and host lists for IP and Web traffic running over a Frame Relay PVC, or look at vital statistics and information for any switched port in a Switched LAN environment.

Among its other management functions, WebCast can bill and charge back network users to help administrators control costs. WebCast software's embedded security lets network managers regulate access to ensure that sensitive information is viewed only by people who need to see and work with it. WebCast embedded security can create groups of users authorized to view any combination of auto reports, on-demand individual reports, alarming or SQL queries. Access to information is set by the network manager and the privileges are activated at the time of user log-on.

WebCast automatic polling updates reports at intervals selected by the network administrator, so the information is always current. The reports can be updated daily, weekly, monthly, or all three. WebCast also formats the reports so that busy network administrators can review the information quickly. This reduces management overhead on the network by gathering the data only once, an approach that eliminates repeat traffic and reserves valuable bandwidth for mission-critical applications and communications. Java-based traps and alarms are integrated to alert administrators to current or potential problems, before they affect network performance.

WebCast customized queries let users specify their own query criteria for the SQL data base by filling in a simple form. No SQL experience is required. The forms enable users to make a specialized report for a specific network segment or a specific timeframe.

NETscout Server is a polling and data collection engine that supports end-to-end network monitoring by enabling many probes to reside on the network while not clogging it with unnecessary traffic. NETscout Server periodically polls localized servers for data, information, and alarms from RMON-based probes and MIB2 devices, eliminating the traffic caused by constant data transmissions. With NETscout Server, companies can build manageable, scalable networks with extensive instrumentation. With WebCast, any data aggregated at remote sites can be accessed through a Web browser.

WebCast supports virtually an unlimited numbers of users and requires no additional training because it works through universally familiar Web browsers. According to Frontier, WebCast's advanced reporting and management capabilities come at about 3 percent of a dedicated workstation's cost.

WebCast is the first phase in Frontier's program to bring Web-based tools and distributed reporting to network users. The subsequent phases will introduce enhancements to NETscout Server's scalable mid-level management capabilities to allow peer-to-peer report aggregation of RMON information. Eventually, Frontier will introduce a Web interface for all of NETscout Manager's real-time diagnostic and analysis tools.

Cabletron Systems | Vendor Implementations

Cabletron has added several new Web-based capabilities to its Spectrum 4.0 network management system. Enterprise Web Alarm View, for example, allows a user to view alarm data across multiple landscapes from anywhere within their network through a Web browser. This displays the total number of alarm counts for each condition, providing the user a quick reference point of how many alarms of various conditions exist in their network, as well as the total count of all alarms in the network. With the ability to specify the maximum number of alarms which will be listed in the alarm table, the user can control the amount of data that will be presented. The Enterprise Alarm Web is used to view information only; alarm management cannot be performed.

Cabletron also offers a Web-based switch management tool called WebView. This tool allows network managers to configure and monitor Cabletron SmartSwitches through standard Web browsers, while providing access to on-line documentation and context-sensitive help. The easy-to-use graphical interface of standard Web browsers offers a tremendous advantage over traditional text-based interfaces. With WebView, network managers no longer have to struggle with difficult text-based Telnet interfaces, for example, or make trips to the wiring closet with a dumb terminal every time they need to reconfigure a switch.

3Com Corp. | Vendor Implementations

3Com's Web-based tools are designed for both enterprise and small-office markets. Within the enterprise, 3Com offers an external server to provide Web-based access to network devices, complementing its existing network management system, Transcend Enterprise Manager (TEM). For the small-office environment, 3Com embeds Web server technology into its network devices, giving net administrators with Java-enabled Web browsers direct access to management information about these devices. Even though these devices, such as OfficeConnect, are self-configuring, they will require a certain amount of monitoring and managing, which will be provided by an embedded Web server and the Web-based management applications.

Via a standard Web browser any node on the network, the authorized user connects to the corporate intranet and accesses the URL of the device to be managed. Once password access is granted, a graphic representation of the device is shown, along with performance statistics. From desktops anywhere on the corporate intranet and using simple point-and-click actions, managers can perform such functions as:

§  Do installation, configuration, and maintenance

§  Access device-specific views

§  Run diagnostic tests

§  Perform troubleshooting tasks, such as enabling/disabling ports or achieve auto-load balancing to optimize network performance

§  Access historical data of the device's performance over time

Although there are many net management products available with Web front-ends, 3Com's TEM goes beyond them by offering true interactivity. While other products offer only static views of various information, such as an event log, 3Com's fully functional interface allows not only viewing from the Web, but lets actual configuration tasks to be performed. A home page feature, called Transcend Central, provides a single view of all 3Com equipment. This gives users a starting point from which to launch various management tools and facilitates navigation.

Cisco Systems | Vendor Implementations

Cisco Systems, Inc. offers a suite of Web-based device management applications that let users administer networks of Cisco routers and switches from a Web browser. Called Cisco Resource Manager (CRM), the suite includes applications that let users track everything from device inventory to software configurations. CRM also analyzes Internetwork Operating System (IOS) event messages generated by network devices.

The server-based CRM shares data with Hewlett-Packard Co.'s OpenView management platform, letting OpenView administrators have full view of the Cisco environment. CRM's Web-based management capabilities are promising because they let users manage complex router environments from a simple, inexpensive, easy-to-use Web browser. Web browsers also run on multiple platforms, so users would no longer have to depend on Unix-based workstations as they do in the OpenView environment and other industry-leading management platforms.

CRM resides on Solaris and Windows NT-based Web servers. From a Web browser, a user can invoke CRM by typing in a URL to load the product's HTML page. From there, hotlinked commands allow the user to access inventory, software, and availability data from IOS agents that support HTTP on Cisco routers and switches.

CRM also can launch Java applets for more real-time interaction with Cisco devices and enhanced graphical representation. The inventory application within CRM keeps tabs on the type and configuration of Cisco devices in the network. The software image manager allows users to determine the version of IOS running on the devices and load or update a version.

Bay Networks | Vendor Implementations

As part of its strategy to exploit intranets as a means for making system-wide network management information available across the enterprise, Bay Networks has added Web-based monitoring and viewing capabilities to its Optivity application suite. Optivity Web provides network managers and operations staff with real-time information on network performance, faults, and network usage patterns. Specifically, Web-based management is supported through the NetReporter trending and reporting application. NetReporter produces network usage information that can be automatically exported to a corporate Web server and viewed as needed, giving users access to the important data they need.

Bay Networks' architectural framework for delivering Web-based network management solutions features three distinct elements: the nearly universal Web browser itself; Web-enabled management applications; and HTTP-enabled devices. The framework provides network managers with direct access to individual devices and to Optivity capabilities via a Web browser. While this solution greatly simplifies overall management and makes information more universally available, several key points are worth noting:

§  Network management application processing must still be provided, although the location of the processing will evolve over time.

§  Devices must continue to become more intelligent to support functions like multilayer topology and RMON2, regardless of the shift to Web-based management tools and access.

§  Management will continue to use SNMP and any other management protocols that may become standardized, until SNMP access to legacy equipment is no longer an issue.

Optivity's object-oriented Enterprise Command Center (ECC), which offers a concise summary of all sites within the network, is Web accessible from anywhere in the enterprise. From Web access to ECC, users can launch and work with Java-based Optivity applications, including OmniView and the Enterprise Health Advisor for graphical fault management of the network.

With these Web-accessible tools, network operations staff can access detailed information from home or any desktop. OmniView is a network statistics viewing and integration tool that provides Java-based tabular and graphical output to show the state of devices and networks. OmniView can gather data from a variety of standard MIBs, including MIB II, RMON, Repeater, and ATM MIBs, as well as access advanced functionality provided in Bay Networks proprietary MIBs. Enterprise Health Advisor monitors the status of all routers, hubs, and switches in the enterprise and identifies devices with fault or performance problems, and correlates faults for each device in the network.

Optivity ECC is a topology viewer that uses an intuitive file-folder paradigm to display all devices by type—hub, router, or switch—grouped by campus or region for easier manageability. The application leverages Bay Networks' Autotopology multilayer topology feature, which automatically discovers all network devices, as well as their physical and logical relationships. ECC eases policy management by providing the ability to view and act on all devices of a certain type in one screen, rather than having to navigate across subnet views as is the case in the typical network management system map. Upon drilling down to a particular device of interest, ECC provides launch-point integration to a variety of system and device level applications, as well as simple connectivity testing such as ping.

Bay Networks also offers Web-enabled devices for remote configuration and monitoring in the device. The BayStack line of stackable hubs and routers is among the product lines to be outfitted with Web server technology, which provides forms-based configuration, performance statistics, and device fault logs. Links to on-line help and documentation, as well as to Bay Networks' corporate Web site, are also provided.

Implementation Strategies | Web-Based Management

Two basic strategies for implementing WBM are evolving: the proxy solution and the embedded approach. While these methodologies are not mutually exclusive, each has its advantages.

Proxy solution

The proxy solution adds a Web-based server to an intermediate station (the proxy), which interconnects with the end devices that it manages (Figure 1). Users access the proxy through a Web browser, using the HyperText Transmission Protocol (HTTP), while the proxy accesses end devices SNMP. Usually, this approach adds a Web server to an existing management product, which optimizes functions such as database access and SNMP polling. This approach maintains the advantages of workstation-based management systems while adding flexible access to intranet data. Since the proxy communicates with all the managed devices, the administrator can view all or portions of the enterprise's networks, servers, and desktops, as well as such logical entities as virtual LANs. Since the proxy-to-device protocol remains SNMP, this approach also works with SNMP-only devices. However, the proxy technique does require a workstation.

Figure 1: The proxy solution for WBM.

Embedded approach

The embedded method actually installs a Web server in the end device. Each device has its own Web address, and the administrator uses a Web browser to visit the managed devices (Figure 2). This approach allows graphical management of individual devices. It is a simpler interface than today's system management tools and offers easier operation with no sacrifice in functionality.

Figure 2: The embedded approach to WBM.

Many organizations will probably end up using both proxy-based and embedded Web server capabilities. Large organizations will need the enterprise-wide monitoring and management capabilities that are available only with the proxy solution. The proxy solution can also manage SNMP-only devices. In conjunction with proxy-based servers, large corporations could also benefit from embedded Web servers because of their simple setup requirements and their ability to manage new devices.

The embedded Web server approach is especially well suited for managing small branch offices. These networks are relatively simple and typically do not require powerful management systems or need enterprise-wide views. Users at these remote locations usually are not familiar with device-control and network procedures. Embedded Web servers allow these users to become operational quickly with minimal instruction. Although the plug-and-play nature of Web-based devices simplifies installation and minimizes troubleshooting, they do not necessarily limit device-level capabilities.

A Web browser can communicate directly with networked devices using HTTP. The most common reasons for connecting directly to individual network devices include configuration and reconfiguration, simple status monitoring, and implementing specific corrective actions. For small networks, this approach alone might be a sufficient management solution; for larger networks, this approach will typically supplement more global tools in a variety of circumstances, including the final stages of problem resolution.To support large-scale management, however, devices will have to continue collecting and providing remote monitoring (RMON) and multilayer topology data. Critical network devices will need these capabilities to support network systems applications.

Managing an enterprise network requires the collection and correlation of voluminous amounts of data. This type of processing is still required in order to understand and manage the network. As the era of Web-based management unfolds, more of this processing can be distributed through Java. This network processing must include such functions as correlation and presentation of network statistics, automatic baselining capabilities, and a single common point for launching all network management activities.

The technology behind these advanced management functions is the intelligent agent—software embedded in network devices that collect both RMON and RMON2 data and multilayer topology information. RMON and RMON2 data provide a detailed view of the characteristics of traffic flowing through the network, while multilayer topology information provides the management application with detailed knowledge of the physical and logical relationships between networked devices. The multilayer topology capability is important for managing a switched network, while RMON is critical to the monitoring and troubleshooting of client/server traffic.

LAN implementation | Microwave

LAN implementation

There are some short haul microwave systems used for corporate LANs that do require an FCC license because they operate in a more crowded portion of the spectrum. This is the case with the 18-GHz frequency band, which is used by Motorola's Altair product line, for example. The FCC allocates licenses for the 18-GHz region of the spectrum for five channels, each consisting of two 10-MHz bands in the 18- to 19-GHz band. The two-channels-per-license arrangement permits full-duplex communications using one channel in each direction.

While a license may be construed as a liability, it offers the guarantee of interference-free communication. Unlike unlicensed spectrum, such as that often used by spread-spectrum technologies, licensed spectrum gives the license-holder a legal right to an interference-free data communications channel. Owners of wireless LANs operating on unlicensed spectrum are continuously at risk of unauthorized interference destroying their data communications capabilities, and do not always have legal recourse.

Since Motorola has obtained licenses for 18-GHz operation in all U.S. metropolitan areas with populations above 30,000, Altair microcells in these areas are fairly well protected from unauthorized interference. Motorola customers do not have to deal directly with the government or wait for approval to operate Altair equipment. Upon purchasing the equipment, they fill out a simple registration form, and immediately place their equipment into operation. Motorola's Frequency Management Center dedicates and coordinates frequencies to specific customer locations. In the event a customer moves the Altair system to another location, Motorola provides an 800 number to report that fact in compliance with FCC requirements. Motorola handles frequency coordination for the customer at the new location.

LAN extension

Corporations are making greater use of wireless technologies for extending the reach of LANs where a wired infrastructure is absent or costly. Wireless bridges and routers can extend data communication between buildings in a campus environment or between buildings in a metropolitan area.

Wireless bridges. Short-haul microwave bridges equipped with directional antennas provide an economical alternative to leased lines or underground cabling. Because they operate over very short distances—less than a mile—and are less crowded, they are less stringently regulated and have the additional advantage of not requiring an FCC license.

The range of the bridge is determined by the type of directional antenna. A 4-element antenna, for example, provides a wireless connection of up to 1 mile. A 10-element antenna provides a wireless connection of up to 3 miles.

Directional antennas require a clear line of sight. To ensure accurate alignment of the directional antennas at each end, menu-driven diagnostic software is used. Once the antennas are aligned, and the system ID and channel are selected with the aid of configuration software, the system is operational. Front-panel LEDs provide a visual indication of link status and traffic activity. The bridge unit has a diagnostic port, allowing performance monitoring and troubleshooting through a locally attached terminal or remote computer connected via modem.

Because it is fully compatible with the IEEE 802.3 Ethernet standard, microwave bridges support all Ethernet functionality and applications without the need for any special software or network configuration changes. For Ethernet connections, the interface between the microwave equipment and the network is virtually identical to that between the LAN and any cable medium, where retiming devices and transceivers at each end of the cable combine to extend the Ethernet cable segments. Typically, microwave bridges support all Ethernet media types via AUI connectors for thick Ethernet (10Base5), 10Base2 connectors for thin Ethernet, and twisted-pair connectors for 10BaseT Ethernet. These connections allow microwave bridges to function as an access point to wired LANs.

Like conventional Ethernet bridges, microwave bridges perform packet forwarding and filtering to reduce the amount of traffic over the wireless segment. The microwave bridges contain Ethernet address filter tables, which help to reduce the level of traffic through the system by passing only the Ethernet packets bound for an interbuilding or intrabuilding destination over the wireless link. Since the bridges are "self-learning," the filter tables are automatically filled with Ethernet addresses as the bridge learns which devices reside on its side of the link. That way, Ethernet packets that are not destined for a remote address remain local. The table is dynamically updated to account for equipment that is either added or deleted from the network. The size of the filter table can be 1000 entries or more, depending on vendor.

With additional hardware, microwave bridges have the added advantage of pulling double-duty as a backup to local T1/E1 facilities. When a facility degrades to a pre-established error-rate threshold or is knocked out of service entirely, the traffic can be switched over to a wireless link to avoid loss of data. When line quality improves or the facility is restored to service, the traffic is switched from the wireless link to the wireline link.

Wireless routers. Wireless remote access routers scale wireless connect geographically disbursed LANs by creating a wireless WAN over which network traffic is routed at distances of 30 miles or more using spread-spectrum technology.

Unlike wireless bridges which simply connect LAN segments into a single logical network, wireless routers function at the network layer with IP/IPX routing, permitting the network designer to build large, high performance, manageable networks. Wireless routers are capable of supporting star, mesh, and point-to-point topologies that are implemented with efficient MAC protocols. These topologies can even be combined in an internetwork.

A polled protocol (star topology) provides efficient shared access to the channel even under heavy loading (Figure 1). For small-scale networks, a CSMA/CA protocol supports a mesh topology (Figure 2). Clusters of nodes can be connected using a point-to-point protocol when building large-scale internetworks (Figure 3). The single-hop node-to-node range is up to 30 miles, depending on such factors as terrain and antennas, with a multiple hop range extending on the order of a hundred miles.

Figure 1: In the star topology, remote stations interconnect with the central base station, and with other remote stations, through the base station. Only one location needs line-of-sight to the remotes. Networks and workstations at each location tie into a common internetwork. The maximum range between the central base station and remote stations is approximately 15 miles.

Figure 2: In the mesh topology, each site must be line-of-sight to every other. A CSMA/CA protocol ensures efficient sharing of the radio channel. The range with omni-antennas is up to 3.5 miles.

Figure 3: The point-to-point topology is useful where there are only two sites. It can also function as a repeater link between clusters of sites. The range using directional antennas is up to 30 miles.

End-to-end SNMP supports management of the radios and the wireless WAN along with the remainder of the enterprise network using industry standard SNMP tools. The result is a manageable network with reach extending to metropolitan, suburban, rural, remote, and isolated areas.

Applications of wireless routers include remote site LAN connectivity and network service dissemination. Organizations with remote offices such as banks, health care networks, government agencies, schools, and other service organizations can connect their computing resources. Industrial and manufacturing companies can reliably and cost-effectively connect factories, warehouses, and research facilities. Network service providers can distribute Internet, VSAT, and other network services to their customers.

A WAN built with wireless routers exploits the tariff-free wireless "infrastructure." A wireless WAN offers a substitute for a wired infrastructure with its associated costly service fees. In areas where a wired infrastructure is absent or underdeveloped, the use of wireless routers newly enables internetworking. Performance is comparable to commonly used wired WAN connections, approaching T1 speeds with a 1.3 Mbps data rate.

A user-supplied PC hosts the wireless router device through a connection to the PC's parallel printer port. Software includes an installation utility, network drivers, management, and IP/IPX routing. No radio license is required in the United States and many other countries, simplifying the network development process compared to licensed microwave.