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<FONT FACE="Verdana, Arial, Times New Roman" SIZE=5><H2>NTttcp</H2>
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<P><span style="color:#FF0000;font-size:10pt;font-family:Arial">[This is preliminary 
documentation and subject to change.]</span></P>

<H3>SUMMARY</H3></FONT><FONT FACE="Verdana, Arial, Times New Roman" SIZE=2><P>
This tool measures network driver performance and throughput on different network topologies and hardware setups.  It provides the customer with a multi-threaded, asynchronous performance benchmark for measuring achievable data transfer rate on an existing network setup.<p>

<H3>BUILDING THE SAMPLE</H3></FONT><FONT FACE="Verdana, Arial, Times New Roman" 
SIZE=2><P>

The Microsoft&reg; Windows&reg;&nbsp;2000 DDK includes the NTttcp executable.  No build is required. Note that the same executable is present under two filenames, <i>Ntttcpr.exe</i> (receiver) and <i>Ntttcps.exe</i> (sender).<p>

<H3>USAGE</H3>

<b>Syntax</b><p>

NTttcpR -m 4,0,11.1.1.200 -a [-l | -n | -p | -b | -sb | -rb | -z | -w | -v]<br>
NTttcpS -m 4,0,11.1.1.200 -a [-l | -n | -p | -b | -sb | -rb | -z | -w | -v]<p>

<b>Parameters List and Default Values</b><p>
-l specifies the length of the buffer (default: 64K)<br>
-n specifies number of buffers being used (default: 20K)<br>
-p specifies the port number being used<br>
-b disables TCP_NODELAY<br>
-sb specifies the SO_SNDBUF size (default: zero)<br>
-rb specifies the SO_RCVBUF size (default: 64K)<br>
-z disables Virtual Allocation in memory<br>
-w disables initial Warm-Up period <br>
-a specifies asynchronous mode (default: four)<br>
-v specifies verbose mode<br>
-m is for mapping, and is followed by threads per link, processor number to which to set affinity, and IP address of receiver machine<p>

Note that changing the following registry parameters may affect your results:<p>

1. <b>HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Ndis\Parameters\NdisAffinityMask</b> <br>
This value defaults to 0xFFFF. Changing this to zero may affect throughput.<p>
2. <b>HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\TcpWindowSize</b><br>
This parameter is not in the registry by default. Set it to 0xFFFF.
Also, make sure the -a parameter is specified in both <i>ntttcps.exe</i> and <i>ntttcpr.exe</i>.<p>

You can run NTttcp over multiple LANs A, B, and C as follows:<p>
NTttcpS -m 4,0,11.1.1.200  3,0,11.1.1.201  5,1,11.2.1.200 -a -n 5000<p>

 LAN A has 4 threads running over processor 0 going to IP 11.1.1.200<br>

 LAN B has 3 threads running over processor 0 going to IP 11.1.1.201<br>

 LAN C has 5 threads running over processor 1 going to IP 11.2.1.200<p>

     Number of buffers is set to 5000, and this is in ASYNC mode.<p>

 When writing small packet lengths (< 1460 bytes), disable Virtual Memory Allocation.<br>

 When writing small packet lengths (< 1460 bytes), set SO_SNDBUF to 64K on sender system and SO_RCVBUF to zero on receiver system.<br>

 Make sure the IP address of the receiver exists in both <i>ntttcpr</i> and <i>ntttcps</i>.<br>




<p>
<H3>CODE TOUR</H3>
<H4>File Manifest</H4>
</FONT><U><PRE>File&#9;&#9;Description
</U>
<i>Ntttcp.htm</i>&#9;Documentation for this tool (this file).
<i>Ntttcpr.exe</i>&#9;NTttcp receiver executable. 
<i>Ntttcps.exe</i>&#9;NTttcp sender executable. 

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