NetTach Help
Preliminary and Confidential - Beta-2 Draft - 10/30/97 1
Table of Contents
What Is NetTach? .......................................................................................................................3
How Does NetTach Work?......................................................................................................3
What Else Can You Do With NetTach?...................................................................................3
Installing NetTach........................................................................................................................4
System Requirements.............................................................................................................4
Running NetTach Tests...............................................................................................................4
Running a Test Using the NetTach Configuration Wizard........................................................5
Running a Test Using the Network Options Dialog Box...........................................................5
Running a Test Using QuickStart............................................................................................5
Using Advanced NetTach Options ..........................................................................................6
Testing a Connection Over Time ....................................................................................6
Creating a Log File .........................................................................................................7
Importing Log Files into Excel.........................................................................................7
Determining a Connection’s Bandwidth Threshold...........................................................7
Displaying NetTach Results .........................................................................................................7
Displaying the Summary Screen.............................................................................................7
Displaying the Statistics View Screen .....................................................................................8
Displaying the Jitter View Screen ............................................................................................8
Definitions
packet loss..............................................................................................................................8
out of order packets................................................................................................................8
jitter........................................................................................................................................8
transfer rate............................................................................................................................8
Illustrations
The Status Bar........................................................................................................................9
The Jitter View Screen............................................................................................................ 9
The Statistics View Screen ...................................................................................................10
The Network Options Dialog Box (General Tab) ...................................................................10
The Network Options Dialog Box (Admin Tab)......................................................................11
The Network Options Dialog Box (Advanced Tab) ................................................................12
The Summary Screen ...........................................................................................................12
The Excel Text Import Wizard..............................................................................................13
Index.........................................................................................................................................14
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What Is NetTach?
NetTach is a program that tests a computer-to-computer network connection and tells you if the
connection is capable of supporting H.323 videoconferencing.
NetTach does this by sending and receiving data packets between two personal computers. The
data packets are sized and transmitted with a frequency similar to the traffic generated by
videoconferencing endpoints such as PictureTel LiveLAN, Microsoft NetMeeting, and PictureTel
Venue/VIU.
NetTach is designed to be used by anyone, no matter what their level of network experience. To
use the advanced features as effectively as possible, though, it’s helpful to understand basic
network terms and concepts.
How Does NetTach Work?
NetTach runs simultaneously on two computers. One computer runs NetTach in sender mode,
transmitting packets of data to the second computer. The second computer runs NetTach in
receiver mode, gathering information about the packets received, then looping them back to the
sender.
When the test cycle ends, NetTach displays the information on a variety of screens, allowing you
to choose the level of detail and format you wish to view.
What Else Can You Do With NetTach?
Beyond performing a simple test of a computer-to-computer data transmission, you can use
NetTach to:
Display test results a variety of ways - NetTach displays basic test results on the Summary
screen, but it also provides more advanced test results through the Statistics View screen and
the Jitter View screen.
Test a connection over time - For more in-depth network analysis, NetTach can collect data
over a 24-hour (or longer) period. It writes this data into a log file that can be imported by a
spreadsheet program to help analyze the data. See Creating Log Files and Importing Log Files
into Excel.
Determine a connection’s bandwidth threshold - You can run a test to find the maximum
amount of bandwidth a network connection can support. See Determining a Connection’s
Bandwidth Threshold.
Manually configure your own tests - If you’re a network expert, you can adjust a wide variety
of parameters to set up your own tests. See Using the Network Options Dialog Box.
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To Install NetTach
You must install NetTach on both the receiving and the sending computers. You can install
NetTach on many receivers and many senders - as many computers as you would like to test. It
is best to install NetTach on the computer you intend to use as your NetTach receiver first.
System Requirements: To install and run NetTach, both the receiving and the sending
computer must have a 32-bit operating system (either Windows 95 or Windows NT 4.0 Server or
Workstation) and support for the TCP/IP protocol.
1. Copy the NetTach files from the NetConference CD-ROM to an appropriate location on the
computer you intend to use as your NetTach receiver.
2. Double click setup.exe.
The InstallShield wizard automatically installs NetTach. Answer the questions according to
what is appropriate for your environment, specifying this system as the Receiver.
3. Go to the computer you intend to use as your NetTach sender and copy the NetTach files
from the NetConference CD-ROM to an appropriate location on the computer.
4. Double click setup.exe.
The InstallShield wizard automatically installs NetTach. Answer the questions according to
what is appropriate for your environment, specifying this system as the Sender.
Note that to run a NetTach test, you must start NetTach on the receiving computer first.
Running NetTach Tests
There are several ways you can run NetTach tests:
Using the NetTach Configuration Wizard: This easy-to-follow wizard lets you configure and
run a simple test in just seconds. The wizard is the best choice for first-time NetTach users.
Using the Network Options Dialog Box: This dialog box lets you select a variety of test
parameters for performing more detailed tests.
Using QuickStart!: Once you’ve selected and saved your testing options, you can select
QuickStart! to immediately run the test.
Using Advanced NetTach Options: This section describes more advanced ways you can test
with NetTach.
Note that you must start NetTach on the receiving computer first!
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To Run a Test Using the NetTach Configuration
Wizard
The NetTach Configuration Wizard helps you configure NetTach to run a simple test quickly and
easily. First-time NetTach users should use the Configuration Wizard to become familiar with
NetTach. The Wizard screens provide information to help you make the choices appropriate for
your environment.
1. Click the Wizard icon .
2. Answer the questions on each Wizard screen or accept the defaults by clicking Next.
The Wizard begins running the test automatically. Watch the status bar, on the bottom of the
main NetTach window, for real-time information about the test.
When the test is complete, the Summary screen appears.
To Run a Test Using the Network Options Dialog
Box
1. Click the Network Options icon .
2. On the General tab, click the application or data rate you wish to simulate.
3. Select Sender or Receiver mode.
4. If you selected Sender, enter either the remote host name or the IP address under
Remote Host.
5. Click the Admin tab.
6. Change or accept the defaults for the Jitter Limits, Packet Loss, and Iterations.
7. Check the desired options under Program Control.
8. Click the Advanced tab.
9. Select the TCP/IP connection type.
10. Specify a Port Number.
11. Type in the Packet Parameters, Packet Rate, and Timeout.
12. Check AutoScan only if you want to determine a connection’s bandwidth threshold.
13. Click Start.
The Advanced tab options must match on the sending and the receiving computers.
To Run a Test Using QuickStart!
1. Click QuickStart! on the NetTach main screen.
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2. Click Sender or Receiver.
3. If you selected Sender, type the name or the IP address of the receiver in the Remote Host
field.
4. Click Start.
QuickStart! runs a NetTach test using the default settings for PictureTel LiveLAN.
Using Advanced NetTach Options
You can perform the following advanced options using NetTach:
Testing a Connection Over Time
Creating Log Files
Importing Log Files into Excel
Determining a Connection’s Bandwidth Threshold
To Test a Connection Over Time
You can evaluate how a network connection behaves over time by running NetTach continuously
for a day or longer. The resulting information is automatically captured in log files. You can
import the log file data into Microsoft Excel, or another spreadsheet application. This information
illustrates the bigger picture of overall network performance.
To test a connection over a 24-hour period, change the number of test iterations from 1 to 1040.
A log file with the results of the test will be created.
Log files for tests run over a 24-hour (or longer) period contain the same information that is
displayed after a short test. Each entry on the log file includes the following information:
n time stamp from the receiving computer
n sending computer’s IP address
n jitter
n transfer rate
n packets lost
n packets out of order
n clock delta [the difference between the clocks on the sender and the receiver]
To Create a Log File
1. On the sending computer, click the Network Options icon .
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2. On the Admin tab, check the Log Results check box or set the number of iterations to 1025
or higher.
3. Click Start.
The resulting log file is named automatically with a date-stamp based on the time the test began.
For example, a file named NT07291636.log contains the results of a test on a sender that began
on July 29 at 4:36 p.m. (system time).
To Import Log Files into Excel
Most spreadsheet applications will import a NetTach log file directly because they are in a
standard ASCII, tab-delimited format. This procedure explains how to import a log file using
Microsoft Excel. However, the exact procedure may vary from program to program.
1. In Excel, pull down the File menu and select Open.
2. Select the desired NetTach log file and click Open.
3. Use the Excel Text Import Wizard to import the log file.
Tip: In general, you may accept the defaults selected on the wizard screens, making sure the
Delimited check box is checked.
To Determine a Connection’s Bandwidth
Threshold
To determine a network’s bandwidth threshold, check the Auto Scan check box on the Network
Options Advanced tab, then start the test. The packets are sent with incrementing bandwidth
until the packet loss exceeds the packet loss limitation set on the Network Options Admin tab. At
that point, the test stops and the resulting test data illustrates the highest bandwidth the test
attained.
Displaying NetTach Results
NetTach displays test results on three screens - the Summary screen, the Statistics View screen,
and the Jitter View screen.
Displaying the Summary Screen
Displaying the Statistics View screen
Displaying the Jitter View screen
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To Display the Summary Screen
Ø Click the Summary screen icon at the completion of any test.
The Summary screen assigns a red, green, or yellow light based on the packet loss, out of order
packets, and jitter information generated during the test.
If you check the Show Summary check box on the Network Options Admin tab, the Summary
screen displays automatically at the completion of a test.
To Display the Statistics View Screen
Ø Click the Statistics icon at the completion of any test.
This screen displays all four types of test data (packet loss, out of order packets, jitter, and
transfer rate) in a statistical report.
To Display the Jitter View Screen
Ø Click the Jitter icon at the completion of any test.
This screen displays a variety of details about the last test’s jitter.
packet loss
The number or percentage of data packets that don’t arrive at their destination.
out of order packets
The number or percentage of data packets that arrive at their destination out of sequence. Also
called “out of sequence packets”.
jitter
The number of data packets that arrive at their destination early or late - in other words, not at
their predicted arrival time.
transfer rate
When you see transfer rate on the Summary screen or in a log file, it refers to the actual number
of kilobits per second that the data packets were able to achieve during that test.
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The Status Bar
Status of NetTach - Idle
(test is not running) or
Transfer rate you are trying to
achieve during this test.
Active (test is running).
Status of the test (Transmit or Receive).
The Jitter View Screen
Graph
showing
jitter detail.
You can
scroll this
graph to
view entire
range.
Percentage
indicator.
Shows how
much of the
transmission
(one-way) is
complete.
This line illustrates the average
level of jitter.
This area displays each packet's characteristics.
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The Statistics View Screen
Graph
showing
quality of
packet
order and
loss, and
jitter (high,
medium,
low).
Detailed statistics about packets on each loop.
The Network Options Dialog Box (General Tab)
Specify a
videoconferencing
application's data rate
to simulate.
Brings you to the
Admin or
Advanced tab.
Specify your PC as
a sender or
receiver.
Name or IP address of the
remote computer you are
testing with.
Starts running the
NetTach test.
Saves the settings
chosen on this screen
but does not begin the
test.
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The Network Options Dialog Box (Admin Tab)
Brings you to the General
or Advanced tab.
Number of times the test
runs (usually one). To test
over a 24-hour period, set
this to 1040.
Specify the maximum percentage of lost
packets acceptable for this connection.
Starts running the NetTach
test when you exit this
screen (unless you click
Cancel).
Stores test data in one or
more log files.
Stops testing when
NetTach encounters an
error.
Displays the Summary
screen automatically when
the test is complete.
Starts running the
NetTach test.
Specify what is considered a low or high jitter
rate for each test. Jitter limits may differ among
videoconferencing applications. Limits specified
here are reflected on the Jitter and Statistics
Views.
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The Network Options Dialog Box (Advanced Tab)
Brings you to the General
or Admin tab.
How long the receiver waits
for a response before
stopping the test.
Specify the transfer rate of the
packets for this test.
The type of TCP/IP network connection.
Port number of the system
you are testing with.
Accepts 1024 through
4096.
Define the number of
packets and their size in
bytes.
Tests for maximum
bandwidth allowed for this
connection.
Starts running the
NetTach test.
The Summary Screen
Green light indicates a good
(acceptable) quality connection.
OK to videoconference.
Yellow light indicates a marginal
(medium) quality connection.
Probably acceptable for most
videoconferences. You should
retest periodically.
Red light indicates a poor
(unacceptable) quality connection.
Not suitable for videoconferencing.
Inform network administrator of
this condition.
Summary data
from the test.
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Sample of the Excel Text Import Wizard
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Index
A
Admin tab
sample of ...............................................................................................................................11
advanced NetTach options..........................................................................................................6
Advanced tab..............................................................................................................................5
sample of ...............................................................................................................................11
Auto Scan ...............................................................................................................................5, 7
B
bandwidth threshold.....................................................................................................................7
C
configuration wizard ....................................................................................................................5
creating a log file.....................................................................................................................6, 7
D
description of NetTach.................................................................................................................3
determining a connection’s bandwidth threshold..........................................................................7
displaying NetTach results........................................................................................................... 7
E
Excel...........................................................................................................................................7
Excel text import wizard
sample of ...............................................................................................................................13
G
General tab
sample of ...............................................................................................................................10
H
H.323 videoconferencing .............................................................................................................3
how NetTach works..................................................................................................................... 3
I
importing log files into Excel........................................................................................................ 7
sample of Excel text import wizard.........................................................................................13
installing NetTach........................................................................................................................ 4
J
jitter .........................................................................................................................................8, 9
Jitter View screen
displaying.................................................................................................................................8
sample of .................................................................................................................................9
L
LiveLAN..................................................................................................................................3, 6
log files........................................................................................................................................6
creating....................................................................................................................................6
importing into Excel................................................................................................................. 7
names of..................................................................................................................................7
sample of Excel text import wizard.........................................................................................13
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when testing over time.............................................................................................................6
N
NetMeeting.................................................................................................................................. 3
Network Options dialog box.................................................................................................4, 5, 7
Network Options dialog box (Admin tab)
sample of ...........................................................................................................................7, 11
Network Options dialog box (Advanced tab)
sample of ...............................................................................................................................12
Network Options dialog box (General tab)
sample of ...............................................................................................................................10
O
out of order packets..................................................................................................................... 8
P
packet loss.................................................................................................................................. 8
packets........................................................................................................................................8
Q
QuickStart!..............................................................................................................................4, 5
R
results
displaying.................................................................................................................................7
running a test using QuickStart!............................................................................................... 4, 5
running a test using the NetTach Configuration Wizard ...........................................................4, 5
running a test using the Network Options dialog box................................................................4, 5
running NetTach tests..................................................................................................................4
S
statistics....................................................................................................................................10
displaying the Statistics View screen........................................................................................8
Statistics View screen
displaying.................................................................................................................................8
sample of ...............................................................................................................................10
status bar
sample of .................................................................................................................................9
Summary screen
displaying.................................................................................................................................7
sample of ...............................................................................................................................12
system requirements................................................................................................................... 3
T
testing a connection over time.....................................................................................................6
tests
running ....................................................................................................................................4
text import wizard
sample of ...............................................................................................................................13
threshold .....................................................................................................................................7
threshold testing..........................................................................................................................7
transfer rate................................................................................................................................. 9
V
Venue/VIU................................................................................................................................... 3
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W
wizard..........................................................................................................................................5
sample of Excel text import wizard.........................................................................................13
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