Use this NT Server tool to evaluate application speed across your network
Although network monitoring has been prevalent for decades, many systems administrators are just now recognizing the benefits of proactive network testing. Technology's rapid growth has traditionally placed administrators in a firefighting, reactive mode, so they study the network's functionality only when a device or service goes down. Through proactive network testing, you can measure how applications function under various network conditions. Thus, you can forecast and plan the network's behavior to eliminate future network problems. Regular testing lets you reduce downtime, improve
network performance, speed deployments, increase user satisfaction, and make more efficient use of employee time and company resources.
Testing can also help reduce the cost of purchasing an application. Running a product through tests on your network or in a lab environment is a useful way to determine whether the product will perform up to its specifications, before
you purchase the product. Testing lets you enter negotiations with the vendor
knowing how well the product performs in your production environment and gives
you the expertise to ask the vendor to address the product's limitations. You
can use testing to precisely define hardware requirements for a product before
you make purchases. You don't want to spend money for a quad-processor machine
when a single-processor model will perform adequately, and you don't want to pay
for a point-to-point T1 circuit when a 256 kilobits per second (Kbps)
frame-relay connection provides enough throughput. Determining the application's
network requirements helps you predict how the new application will affect other
applications' traffic on your network.
The costs associated with downtime and application purchases are too great
for you to postpone application testing on your network. (For information about
common types of application testing, see the sidebar "Planning a Test."
) Use the Network Monitor tool that comes with NT Server to test an
application's throughput on your network. Then, analyze the results to diagnose
network bottlenecks for software you already own or to prepare your network for
a new software package.
Using Network Monitor
Network Monitor is a powerful network analyzer that tracks information up to
the network layer, filters packets according to their protocol or their source
or destination machine, and conducts packet analysis. Network Monitor consists
of an agent, which sends packets to the Network Monitor buffer, and tools, which
interpret and report data the agent gathers. (For information about installing
Network Monitor, see Paula Sharick, "A Newbie Meets NT's Network Monitor,"
June 1997, and Curt Aubley, "The Beginner's Guide to Optimizing Windows NT
Server," August 1997.) Click Administrative Tools, Network Monitor on the
Programs menu to open the program.
Network Monitor prompts you to select an agent if your local agent isn't
running. To connect to an agent on another system, select Networks from the
Capture menu in the main Network Monitor window. Select the name of a computer
that is running the agent. You need administrative rights on both machines to
connect to another machine's agent.
After Network Monitor connects to an active agent, the Capture window
appears. Click Start Capture on the window's toolbar (it looks like a play
button). Statistics will begin to accumulate. Screen 1 shows the Capture window
for communications between the local machine, BOZO, and another machine,
0060978FA696. (To instruct Network Monitor to identify machines by their
familiar names instead of their NIC addresses, right-click the address, select
Properties, and enter the machine's NetBIOS name).
Stop the capture to analyze individual packets' statistics. Select Stop
from the Capture menu or click Stop and View on the toolbar (the button's icon
shows glasses over a solid square). The Frame Viewer window will appear.
Double-click a particular frame to display its contents. Screen 2 shows the
Frame Viewer window for communication between two computers, BOZO and KRUSTY,
via the Internet Control Message Protocol (ICMP--the protocol that ping uses).
When I double-click frame 7, the data portion of the frame appears; it consists
of the alphabet in lowercase. This data is the payload (the data segment of the
packet) that Windows NT uses when it sends ping packets.
To analyze an application's throughput, you need only the information in
the top pane of the Frame Viewer window--the source and destination computers,
the packet's departure or arrival time (depending on which computer you perform
the capture on), and which protocol the packet uses. (For more information about
using Network Monitor, see Michael P. Deignan, "Network Monitoring with
SMS," July 1997.)
Setting Up an Application Test
Connect an NT server and NT client that are running Network Monitor to
create a simple test network, as Figure 1 illustrates, or install Network
Monitor on a client and server on your production network. On a test network,
the cloud shape in Figure 1 represents a WAN link or router connection and any
devices you install between your client and server to emulate your production
network. On a production network, the cloud represents all the devices on the
network between the computers that you're running the tests on.