14.3 Network Design Tools

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As with documentation tools, the design process usually starts by opening a blank drawing window from within the design tool into which various vendor-specific devices can be dragged from a product library and dropped into place (see Figure 14.3). The devices are further defined by type of components, software, and protocols as appropriate. By drawing lines, the devices are linked to form a network, with each link assigned physical and logical attributes. Rapid prototyping is aided by the ability to copy objects from one drawing to the next, editing as necessary, until the entire network is built. Along the way, various simulations can be run to test virtually any aspect of the design. This level of intelligence is not found in drawing and documentation tools.

Figure 14.3: A design tool, such as DesignXpert from NetFormx provides workspace into which objects can be dragged-and-dropped from a device library to start the network design process. ( Source: © 2003 Netformx. Reprinted with permission.)

For a network that is already established, the auto-discovery capabilities found in some drawing and design products can be used to help populate a blank workspace. Topology information can also be supplied using the auto-discovery capabilities of such management platforms as Hewlett-Packard’s OpenView and IBM’s Net-View—which automatically detect various network elements and represent them with icons on a topology map. These NMSs also offer other useful information that can be considered in the design process, such as traffic statistics.

Designing a large, complex network requires a multifaceted tool—ideally, one that is graphical, object-oriented, and interactive. It should support the entire network life cycle, starting with the definition of end-user requirements and conceptual design, to the very detailed vendor-specific configuration of network devices, the protocols they use, and the various links between them. At each phase in the design process, the tool should be able to test different design alternatives in terms of cost, performance, and validity. When the design checks out, the tool generates network diagrams and a bill of materials—all this before a single equipment vendor or carrier sales rep is contacted or request for proposal (RFP) is written.

With the right tools, modules, and device libraries, every conceivable type of network can be designed, including legacy networks such as X.25, SNA, and DECnet, voice networks including ISDN, as well as T1, ATM, and TCP/IP nets. Some tools even take into account the use of satellite, microwave, and other wireless technologies like Wi-Fi.

The designer can take a top-down or bottom-up approach to building the network. In the former, the designer starts by sketching out the overall network; subsequent drawings add increasing levels of detail until every aspect of the network is eventually fleshed out. The bottom-up approach might start with a LAN on a specific floor of a specific building, with subsequent drawings linked to create the overall network structure.

As the drawing window is populated, devices can be further defined by type of component such as chassis, interface cards, and daughter boards. Even the operating system can be specified. Attributes can be added to each device taken from the library—to specify a device’s protocol functionality, for example. Once the devices have been configured, a simulation profile is assigned to each device, which specifies its traffic characteristics for purposes of simulating the network’s load and capacity.

With each device’s configuration defined, lines are drawn between them to form the network. With some design tools, the links can be validated against common protocols and network functions. This prevents NetWare clients from being connected to other clients instead of servers, for example. Such on-line analysis can also alert the designer to undefined links, unconnected devices, insufficient available ports in a device, and incorrect addresses in IP networks. Some tools are even able to report violations of network integrity and proper network design practices.

Network Simulation

Once the initial network design is completed, it can be tested for proper operation by running a simulation that describes how the actual network devices behave under various real-world conditions. The simulator generates network events over time, based on the type of device and traffic pattern recorded in the simulation profile. This enables the designer to test the network’s capacity under various what-if scenarios and fine-tune the network for optimal cost and performance. Simulators can be purchased as standalone programs or may be part of the design tool itself.

Some tools are more adept at designing WANs, particularly those that are based on TDMs. With a TDM component taken from the device library, for example, a designer can build an entire T1 network within specified parameters and constraints. The designer can strive for the lowest transmission cost that supports all traffic, for instance, or strive for line redundancy between all TDM nodes. By mixing and matching different operating characteristics of various TDM components, overall design objectives can be addressed, simulated, and fine-tuned. Some tools come with a tariff database to price transmission links and determine the most economical network design.

Such tools may also address clocking in the network design. Clocks are used in TDM networks to regulate the flow of data transmitted between nodes. All clocks on the network must therefore be synchronized to ensure the uninterrupted flow of data from one node to another. The design tool automatically generates a network topology synchronization scheme, taking into account any user-defined criteria, to ensure that there are no embedded clock loops.

Bill of Materials

Once the design is validated, the network design tool generates a bill of materials that includes order codes, prices, and discounts. This report can be exported to any Microsoft Windows application, such as Word or Excel, for inclusion in the proposal for top management review or an RFP issued to vendors and carriers who will build the network. Through the tool’s capability to render multiple device views, network planners can choose either a standard schematic or an actual as-built rendering of the cards and the slot assignments of the various devices. Some tools also generate Web-enabled output, which allows far-flung colleagues to discuss and annotate the proposal over the Internet—even allowing each person to drill-down and extract appropriate information from the network device library.

The most popular network drawing and documentation tool is Visio Professional from Microsoft. It is used to document existing networks and plan new ones, develop proposals for new infrastructure and directory services, including Active Directory, Novell Directory Services (NDS), and other Lightweight Directory Access Protocol (LDAP)–based directories. Also included in Visio Professional is an extensive collection of clip art that can be kept current with an annual subscription, a scanner and digital camera interface, and photo-editing tools. Visio Professional 2002 is available in 13 languages and for Windows users getting started is very intuitive.

Although Visio is a powerful product, it is best suited for technical professionals. It can be daunting for the average user in a small to medium-size business who just wants to draw presentation-quality network diagrams, without having to learn a complex program. For this level of user, SmartDraw is a viable alternative to Visio, offering support for MS Office and containing 50,000 symbols sorted into 11 collections, including those for networks, floor plans, engineering, and software. A file conversion wizard converts Visio files to SmartDraw files.

For an advanced package that offers more than drawing and documentation capabilities, there are several noteworthy offerings with such capabilities as network monitoring, analysis, and troubleshooting. Fluke Networks, for example, offers Network Inspector. Designed for switched Ethernet LANs, this application works with other packages from Fluke to actively monitor and diagnose problems in TCP/IP, IPX, and NetBIOS environments. Through its discovery process, it pinpoints whether the problems are on the server, client, switch, router, or printer and provides an extensive suite of reports identifying all devices in the LAN and the services they provide. Network Inspector also tightly integrates with Microsoft’s Visio. Any device search will translate itself into a detailed Visio drawing, which can be examined with a high degree of granularity, often down to the port level.

Netformx offers DesignXpert, which supports the design, validation, and procurement phases of the network development process. It offers users a network device library containing over 30,000 images from more than 65 vendors, each of which can be located with the product’s navigation facility. An import/export capability converts between Netformx and Visio. With this capability, network professionals can take existing network documentation and convert it as a baseline for advanced network design or take designs created by Netformx and distribute diagrams in Visio format. Through an annual Web-based subscription service, users can obtain weekly downloads containing thousands of device changes that reflect the latest product changes of equipment manufacturers. DesignXpert can be augmented with a separately priced enterprise auto-discovery capability and an annual subscription to an update service.

NetViz Professional is a network-diagramming and data-visualization tool that uses data-embedded graphics to make hierarchical diagrams that integrate graphics, data, and relationship information across a complex system. Unlike simple diagramming tools, NetViz allows links to an enterprise’s existing data. Instead of creating flat diagrams that can only be viewed one at a time, NetViz creates a comprehensive, enterprise-wide view of all of the infrastructure information important to a business. NetViz also allows users to drag and drop additional graphics into diagrams from virtually any source, including other applications and Web pages. A user simply needs to open an application that has graphics—Visio, PowerPoint, or any clip-art collection—then select a graphic and drag it into a NetViz diagram. It will automatically be incorporated into the NetViz project, where the user can assign data fields to the graphic and link the fields to external data sources. The NetViz package also offers a separately priced Web-server package that allows projects to be saved as Web pages, complete with associated data.

Some of these tools are widely supported by third parties. Altima Technologies, for example, offers a service called NetZoom, which provides tens of thousands of symbols to create professional network documentation using existing applications, including Microsoft Visio, NetViz, and SmartDraw. NetZoom’s database encompasses well-known manufacturers, such as Sun, Cisco, IBM, Dell, and HP, as well as more than 900 other manufacturers. NetZoom includes manufacturer-specific equipment objects for specific networking environments, such as telco, ATM, Ethernet, wireless, broadband and others. NetZoom for Visio includes a 12-month subscription that enables users to download updates or request additional shapes at no additional charge.

There are even companies that specialize in building custom Visio shapes. Visimation, for example, designs shapes for any industry or application, including those for network equipment from such vendors as 3Com, Juniper Networks, Alteon, and Pluris. The company’s shape design expertise can turn a static graphic into an interactive and highly intelligent model of a real-world object.

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