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FOCUS AREAS

SAS/OR Software

Modeling Information Networks

NETWORKS Application

Introduction

Communications networks, whether they are voice, data, or computer, are increasingly important for any size business. The combination of new technology, industry deregulation, and increased competition has forced network service and equipment providers not only to upgrade their own networks and equipment but also to offer many new services and equipment to their customers. Both providers and users of this rapidly changing technology need powerful tools to help them manage and exploit their network investments. The netWorks application addresses this need and can be used to

Communication networks are expensive and continually evolving, so it is important to keep an accurate record of your installed equipment and network configuration. You can use netWorks to create a picture of your network so you can keep tabs on what equipment you have installed and its current location.

If you need to install a new network, or are considering upgrading an existing network, you can use this application to model and evaluate the different possibilities. By building models of competitive proposals and then sampling the performance characteristics of your network configuration, you can better decide which proposal best fits your needs.

Another important, and often overlooked, benefit of a tool like netWorks is that it can be used to create a repository of network equipment information. By keeping up-to-date information on network equipment options in a single, easily accessible location, you not only can make network modification decisions in a timely and effective manor, but you also can make this information readily available to others in your organization.



Application Overview

The netWorks application is a new graphics-oriented SAS application for modeling and simulating telecommunications and computer networks. Using an interactive, user-friendly interface, you create a graphical representation of a network by instantiating and connecting models of telcom and computer equipment. Some of the equipment models and attributes included in netWorks are as follows:

Equipment

Attributes

The terms `model' and `piece of equipment' are used interchangeably throughout the text. A `piece of equipment' actually refers to a model of a piece of equipment you want to include in your network model. If netWorks does not have a model for a piece of equipment, or if some of the characteristics of a particular piece of equipment are not exactly what you need, netWorks provides facilities to extend, modify, or create pieces of equipment. By using the simulation features in netWorks, you can also explore network performance characteristics.

Building a Model Network

Building a model network in netWorks is an intuitive, painless process. You place icons representing models of network equipment (provided in netWorks) on the main application panel and then connect them with lines or arcs. You can create an instance of an equipment model by using either the toolbar or a popup menu from the main application panel.

To copy a piece of equipment from the toolbar, you simply locate the unit with the appropriate equipment icon in the toolbar panel and click with the left mouse button. This depresses the icon. Then, clicking on the main panel background will place a copy of the equipment at that spot. Additional clicks (with the cursor still on the panel background) will continue to create additional copies.

Creating Models Using the Toolbar

Teleset

It is not practical to have all of the equipment models represented in the toolbar. Additional pieces of equipment are accessed through a popup menu. If you depress the right mouse button while the cursor is on the main panel background, a popup menu appears containing entries for all the equipment models known to netWorks. Once you choose a model from the menu, the cursor will change to a crosshair (+) shape. netWorks is waiting for a left mouse click on the panel background to place the new model instance.

There are also several ways to connect the equipment models. Most equipment has hotspots so that when the mouse cursor is on a hotspot, the cursor changes to a shape that indicates the function available at that location. For example, when the cursor is above the right-hand border of a model, it changes to a crosshair. If you depress the left mouse button and drag until the cursor is over another model and then release the mouse button, an arc will be drawn between the two models. You can also use an option in the equipment popup menu to draw an arc.

Browsing or Editing a Model Instance

You can browse or edit the attributes of a piece of equipment via selections in its popup menu.

Menu Access to Edit Features

If you choose the Browse option from the popup menu, a window appears containing a list of all the equipment's attributes and associated values. To modify, add, or delete equipment attributes, you select the Edit option from the popup menu.

Saving and Restoring

It is usually a good idea to save a copy of your model network in a SAS data set for future reference. Use the File/Save As/Model option from the main pulldown menu to open a window for entering the names of the library and data set to store your picture.

To restore a saved network, use the File/Open option of the pulldown menu. A window opens listing your choices for SAS libraries and data sets of saved model networks.

Analyzing a Network

The netWorks application provides features for sampling the performance characteristics of the model network. The network analysis process consists of selecting which attributes you want to investigate, identifying the paths through the network, and then invoking the simulate routine.

Analysis functions are available through the netWorks control panel, visualized via the toolbar.

Control Panel Window

Analyze Control Panel

The Activate pushbutton on the netWorks Control Panel opens a window for selecting the analysis attributes, and the Paths pushbutton opens the Paths Control Panel.

The Paths Control Panel provides several ways to select paths for your analysis. One approach is to identify the paths one at a time, until all desired paths are selected. A more typical technique is to identify the path endpoints and then let netWorks construct the paths between endpoints.

Paths Control Panel Window

Paths Control Panel

When a simulation is running, netWorks continuously selects and traverses paths, concatenating the appropriate attribute values for the equipment models encountered in the path. Values calculated for each path traversal can be displayed via plots and charts and/or saved in a data set. The netWorks animation feature lets you monitor the path traversals.

Extending the Application

The netWorks application provides models for generic classes of telecommunications and computer equipment. Sometimes these models will be sufficient, and sometimes they will not be. Facilities, like a hierarchical browser, are provided for inspecting and altering the default attributes of the equipment models or for creating new models. Changes can be saved in a SAS data set for use in future netWorks sessions.

Hierarchical Browser

Hierarchical Browser

Statistics and Operations Research