Bandwidth triage for users and applications
Bandwidth can be a precious resource, especially for connections between networks. If all your clients and network applications compete for a limited connection (e.g., an Internet gateway), theyand youmight not be getting the best use of your available bandwidth. Centricity Software’s Centerwise 1.11 lets you manage and prioritize network bandwidth access.
Product Installation
Centerwise installation from the product’s CD-ROM is simple but requires planning. You first need to select a Control Point server, the system in your network from which Centerwise will manage bandwidth. Control Points can be anywhere on your network but preferably in close proximity to the connection you’re managing. To manage access to remote connections and bridges between local or remote networks, complex networks might need multiple Control Points. I installed Centerwise on a Windows 2000 Server machine and configured it as my only Control Point. One NIC connected my server to a simple internal test network, and another NIC connected the server (and the test network) to the Internet. I then used Centerwise to manage client Internet access through this gateway.
You also need to install Centerwise Agents on the client workstations you want to manage. Centerwise supports Win2K, Windows NT, and Windows 9x. To install the Agents, I recommend making the product’s cw.ini file available on a network share, then using installation scripts or Win2K Group Policy to force client installations (the product includes a Windows Installer package for Agent software installation). After the software installs and the client reboots, you need to use the Control Panel Centerwise applet to name each workstation’s Control Point server. To make client installations even easier, you can preset the Control Point server name in the cw.ini file that clients install.
Managing Bandwidth
I first invoked Centerwise’s Control Point Statistics program from the CP system tray icon. This icon is the only location from which you can launch Control Point Statistics. The program displayed how much bandwidth my users and computers were using. Although you can use Windows’ tools to gather similar data, Control Point Statistics collects and presents its data in a format that helps you identify bandwidth hogs and decide how to configure bandwidth. Control Point Statistics identifies machines (and their usernames and IP addresses) with established connections. The UI shows the transmit (Tx, in Figure 1) and receive (Rx, in Figure 1) rates and how these rates translate into allotted amounts of bandwidth. Control Point Statistics also shows the amount of bandwidth that the computer is using the time the program captures the data. You can choose a tabular view or live graphical view, which Figure 1 shows.
You administer the Control Point server and its clients from the Centerwise Administrator program. Unfortunately, you can run this program only from the Control Point server you’re administering, making centralized and remote administration difficult (you can use Win2K Server Terminal Services or a similar program to remotely access Centerwise Administrator). According to the vendor, Centerwise 2.0, which Centricity Software has scheduled to release in late July 2001, offers a Web-based administration interface to permit remote administration.
The cable modem that linked my server to the Internet transmits and receives data at different maximum capacities. The first task for which I used Centerwise Administrator was to input these figures into the program.
Before you can use Centerwise Administrator to regulate bandwidth allocation to your network’s users, you need to populate the Users tab in the UI’s left pane. The Users tab entries take the form username@computer_name@domain_name. Because you can’t use wildcards for any entry element, you can’t manage users and computers independently of one another. This limitation means that you can’t set a computer priority level that regulates that machine’s bandwidth access regardless of who’s logged on, and you also can’t set a user priority level that regulates that user’s bandwidth access no matter where that user logs on. According to the vendor, Centerwise 2.0 policies will follow users from machine to machine.
To assign policies to users and their machines, you select a user from the Users tab in the UI’s left pane, then use the Relative priority slider to assign that user a bandwidth-access priority level from 1 (Low) to 8 (Urgent). You can also create user groups and assign them priority levels. You need to save settings to activate them.
More interesting is Centerwise’s ability to set bandwidth priorities for applications that clients access over the network. This feature lets you restrict the bandwidth available to applications that hog bandwidth and aren’t business-related. Application priorities apply only to those machines on which you’ve installed Agents. To set application priorities, you select applications from Centerwise Administrator’s Applications tab and use the Relative priority slider to assign bandwidth priority levels to the applications. For example, to ensure that your company’s order-entry application has a higher priority than Napster, you can assign Napster the level 1 priority, as Figure 2 shows.
Centricity Software prepopulated the Applications tab’s list with common applications, including many versions of Netscape Navigator and Microsoft Internet Explorer (IE). I used the Tools menu’s Define Applications function to add applications to the list. The Define Applications function needs some refinement, such the addition of a browsing feature. (Currently, you need to type in the executable’s name to add its application to the listfor example, you need to type iexplore to add IE to the list.)
After I set priorities, I opened Control Point Statistics again. The UI’s graphical displays let me verify that Centerwise was managing bandwidth as I had configured it to. I quickly noticed that Centerwise imposes user bandwidth priorities only when a connection is being used to capacity. That is, if you’ve assigned a user the lowest priority but he or she is the only person using a connection, he or she will have access to 100 percent of the connection’s bandwidth.