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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-15 18:20:54 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-15 18:20:54 +0000
commit7c720bec5600a9e607c875c670ca30ed351fa4ba (patch)
treec38c9bedf07616180feee6b91a1dbea038500b54 /doc/index.html
parentInitial commit. (diff)
downloadiperf-upstream/2.1.9+dfsg.tar.xz
iperf-upstream/2.1.9+dfsg.zip
Adding upstream version 2.1.9+dfsg.upstream/2.1.9+dfsg
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+<HTML>
+<HEAD>
+<TITLE>Iperf version 2.0.0</TITLE>
+<!-- $Id: index.html,v 1.1.1.1 2004/05/18 01:50:44 kgibbs Exp $ -->
+</HEAD>
+
+<BODY BGCOLOR="#FFFFFF" LINK="#006633" VLINK="#669900" ALINK="#669966">
+
+<CENTER>
+<P><IMG SRC="dast.gif"
+ ALT="Distributed Applications Support Team"></P>
+</CENTER>
+
+<H1>Iperf version 2.0.0</H1>
+
+<H3>May 2004</H3>
+
+<HR><!-- ----- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- -->
+
+<H3>NLANR applications support
+<BR><A HREF="http://dast.nlanr.net/">http://dast.nlanr.net/</A>
+<BR><A HREF="mailto:dast@nlanr.net">&lt;dast@nlanr.net&gt;</A>
+</H3>
+<P><FONT face="arial,helvetica">
+<H1>Iperf User Docs</H1>
+<H4>Mark Gates<br>
+ Ajay Tirumala<BR>
+ Jon Dugan<BR>
+ Kevin Gibbs<BR> </H4>
+
+May 2004
+<P></CENTER>
+[<a href="#compiling">Compiling</A> |
+<A href="#features">Features</A>&nbsp; |
+<A href="#tuningtcp">Tuning a TCP connection</A> |
+<A href="#tuningudp">Tuning a UDP connection</A> |
+<A href="#multicast">Running multicast servers and clients</A> |
+<A href="#ipv6">IPv6 Mode</A> |
+<A href="#repmode">Representative Streams</A> |
+<A href="#daemon"> Running Iperf as a daemon</A> |
+<!--<A href="#adaptive">Adaptive Window Sizes</A> | -->
+<A href="#service">Running Iperf as a Windows Service</A> ]
+<HR>
+<!-- ----- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- -->
+<H2><A name=compiling></A>Compiling</H2>
+
+Once you have the distribution, on UNIX,
+unpack it using gzip and tar. That will create a new directory
+'iperf-&lt;version#&gt;' with the source files and documentation.
+<P>
+
+Iperf compiles cleanly on many systems including Linux, SGI IRIX, HP-UX,
+Solaris, AIX, and Cray UNICOS. Use '<TT>make</TT>' to configure for your OS and
+compile the source code.
+
+<BLOCKQUOTE><PRE>
+
+gunzip -c iperf-&lt;version&gt;.tar.gz | tar -xvf -
+cd iperf-&lt;version&gt;
+./configure
+make
+
+</PRE></BLOCKQUOTE>
+
+To install iperf, use '<TT>make install</TT>',
+which will ask you where to install it. To recompile, the easiest way is to
+start over. Do '<TT>make distclean</TT>' then '<TT>./configure; make</TT>'. See the Makefile
+for more options.
+<P>
+
+If you have problems, please report them to <A href="mailto:dast@nlanr.net">dast@nlanr.net</A> and
+we will try to fix them quickly. <BR>
+
+<HR>
+<!-- ----- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- -->
+
+<H2><A name=features></A>Features</H2>
+<UL>
+ <LI>TCP
+ <UL>
+ <LI>Measure bandwidth
+ <LI>Report MSS/MTU size and observed read sizes.
+ <LI>Support for TCP window size via socket buffers.
+ <LI>Multi-threaded if pthreads or Win32 threads are available. Client and
+ server can have multiple simultaneous connections.
+ <!-- <LI>Suggest the optimal window size for a connection where the OS allows
+ setting window sizes in the granularity of bytes. </LI>--></UL>
+ <LI>UDP
+ <UL>
+ <LI>Client can create UDP streams of specified bandwidth.
+ <LI>Measure packet loss
+ <LI>Measure delay jitter
+ <LI>Multicast capable
+ <LI>Multi-threaded if pthreads are available. Client and server can have
+ multiple simultaneous connections. (This doesn't work in Windows.) </LI></UL>
+ <LI>Where appropriate, options can be specified with K (kilo-) and M (mega-)
+ suffices. So 128K instead of 131072 bytes.
+ <LI>Can run for specified time, rather than a set amount of data to transfer.
+ <LI>Picks the best units for the size of data being reported.
+ <LI>Server handles multiple connections, rather than quitting after a single
+ test.
+ <LI>Print periodic, intermediate bandwidth, jitter, and loss reports at
+ specified intervals.
+ <LI>Run the server as a daemon (Check out <A
+ href="http://www-itg.lbl.gov/nettest">Nettest</A> for running it as a secure
+ daemon).
+ <LI>Run the server as a Windows NT Service
+ <LI>Use representative streams to test out how link layer compression affects
+ your achievable bandwidth.
+
+<!-- <LI>A library of <A
+ href="lib.html">useful functions and C++
+ classes.</A> </LI>
+-->
+</UL>
+<HR>
+<!-- ----- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- --><BR>&nbsp;
+
+<TABLE cellPadding=3 border=1>
+ <TBODY>
+ <TR vAlign=top>
+ <TH align=left>Command line option</TH>
+ <TH align=left>Environment variable option</TH>
+ <TH align=left>Description</TH></TR>
+ <TR>
+ <TH bgColor=#cccccc colSpan=3>Client and Server options</TH></TR>
+ <TR vAlign=top>
+ <TD><A name=format></A><TT>-f, --format <I>[bkmaBKMA]</I></TT></TD>
+ <TD><TT>$IPERF_FORMAT</TT></TD>
+ <TD>A letter specifying the format to print bandwidth numbers in.
+ Supported formats are&nbsp;
+ <PRE>
+&nbsp;&nbsp;&nbsp; 'b' = bits/sec&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 'B' = Bytes/sec
+&nbsp;&nbsp;&nbsp; 'k' = Kbits/sec&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 'K' = KBytes/sec
+&nbsp;&nbsp;&nbsp; 'm' = Mbits/sec&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 'M' = MBytes/sec
+&nbsp;&nbsp;&nbsp; 'g' = Gbits/sec&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 'G' = GBytes/sec
+&nbsp;&nbsp;&nbsp; 'a' = adaptive bits/sec&nbsp;&nbsp; 'A' = adaptive Bytes/sec
+ </PRE>
+ The adaptive formats choose between kilo- and mega- as appropriate. Fields
+ other than bandwidth always print bytes, but otherwise follow the
+ requested format. Default is 'a'.&nbsp; <BR><I>NOTE:</I> here Kilo = 1024,
+ Mega = 1024^2 and Giga = 1024^3 when dealing with bytes. Commonly in networking,
+ Kilo = 1000, Mega = 1000^2, and Giga = 1000^3 so we use this when dealing with
+ bits. If this really bothers you, use -f b and do the math.</TD></TR>
+ <TR vAlign=top>
+ <TD><A name=interval></A><TT>-i, --interval <I>#</I></TT></TD>
+ <TD><TT>$IPERF_INTERVAL</TT></TD>
+ <TD>Sets the interval time in seconds between periodic bandwidth, jitter,
+ and loss reports. If non-zero, a report is made every <I>interval</I>
+ seconds of the bandwidth since the last report. If zero, no periodic
+ reports are printed. Default is zero.</TD></TR>
+ <TR vAlign=top>
+ <TD><A name=len></A><TT>-l, --len <I>#[KM]</I></TT></TD>
+ <TD><TT>$IPERF_LEN</TT></TD>
+ <TD>The length of buffers to read or write. Iperf works by writing an
+ array of <I>len</I> bytes a number of times. Default is 8 KB for TCP, 1470
+ bytes for UDP. Note for UDP, this is the datagram size and needs to be lowered when using
+ IPv6 addressing to 1450 or less to avoid fragmentation. See also the <A
+ href="#num">-n</A>
+ and <A
+ href="#time">-t</A>
+ options.</TD></TR>
+ <TR vAlign=top>
+ <TD><A name=print_mss></A><TT>-m, --print_mss</TT></TD>
+ <TD><TT>$IPERF_PRINT_MSS</TT></TD>
+ <TD>Print the reported TCP MSS size (via the TCP_MAXSEG option) and the
+ observed read sizes which often correlate with the MSS. The MSS is usually
+ the MTU - 40 bytes for the TCP/IP header. Often a slightly smaller MSS is
+ reported because of extra header space from IP options. The interface type
+ corresponding to the MTU is also printed (ethernet, FDDI, etc.). This
+ option is not implemented on many OSes, but the read sizes may still
+ indicate the MSS.</TD></TR>
+ <TR vAlign=top>
+ <TD><A name=port></A><TT>-p, --port <I>#</I></TT></TD>
+ <TD><TT>$IPERF_PORT</TT></TD>
+ <TD>The server port for the server to listen on and the client to connect
+ to. This should be the same in both client and server. Default is 5001,
+ the same as ttcp.</TD></TR>
+ <TR vAlign=top>
+ <TD><A name=udp></A><TT>-u, --udp</TT></TD>
+ <TD><TT>$IPERF_UDP</TT></TD>
+ <TD>Use UDP rather than TCP. See also the <A
+ href="#bandwidth">-b</A>
+ option.</TD></TR>
+ <TR vAlign=top>
+ <TD><A name=window></A><TT>-w, --window <I>#[KM]</I></TT></TD>
+ <TD><TT>$TCP_WINDOW_SIZE</TT></TD>
+ <TD>Sets the socket buffer sizes to the specified value. For TCP, this
+ sets the TCP window size. For UDP it is just the buffer which datagrams
+ are received in, and so limits the largest receivable datagram size.</TD></TR>
+ <TR vAlign=top>
+ <TD><A name=bind></A><TT>-B, --bind <I>host</I></TT></TD>
+ <TD><TT>$IPERF_BIND</TT></TD>
+ <TD>Bind to <I>host</I>, one of this machine's addresses. For the client
+ this sets the outbound interface. For a server this sets the incoming
+ interface. This is only useful on multihomed hosts, which have multiple
+ network interfaces.&nbsp;
+ <P>For Iperf in UDP server mode, this is also used to bind and join to a
+ multicast group. Use addresses in the range 224.0.0.0 to 239.255.255.255
+ for multicast. See also the <A
+ href="#ttl">-T</A>
+ option.</P></TD></TR>
+ <TR vAlign=top>
+ <TD><A name=compatibility></A><TT>-C, --compatibility </TT></TD>
+ <TD><TT>$IPERF_COMPAT</TT></TD>
+ <TD>Compatibility mode allows for use with older version of iperf. This mode
+ is not required for interoperability but it is highly recommended. In
+ some cases when using representative streaming you could cause a 1.7 server
+ to crash or cause undesired connection attempts.</P></TD></TR>
+ <TR vAlign=top>
+ <TD><A name=mss></A><TT>-M, --mss <I>#[KM}</I></TT></TD>
+ <TD><TT>$IPERF_MSS</TT></TD>
+ <TD>Attempt to set the TCP maximum segment size (MSS) via the TCP_MAXSEG
+ option. The MSS is usually the MTU - 40 bytes for the TCP/IP header. For
+ ethernet, the MSS is 1460 bytes (1500 byte MTU). This option is not
+ implemented on many OSes.</TD></TR>
+ <TR vAlign=top>
+ <TD><A name=nodelay></A><TT>-N, --nodelay</TT></TD>
+ <TD><TT>$IPERF_NODELAY</TT></TD>
+ <TD>Set the TCP no delay option, disabling Nagle's algorithm. Normally
+ this is only disabled for interactive applications like telnet.</TD></TR>
+ <TR>
+ <TD><TT>-V </TT>(from v1.6 or higher)</TD>
+ <TD>.</TD>
+ <TD>Bind to an IPv6 address <BR>Server side: <BR>$ iperf -s -V&nbsp;
+ <P>Client side: <BR>$ iperf -c &lt;Server IPv6 Address&gt; -V
+ <BR>&nbsp;</P>Note: On version 1.6.3 and later a specific IPv6 Address does
+ not need to be bound with the <A href="#bind">-B</A> option, previous 1.6
+ versions do. Also on most OSes using this option will also respond to IPv4
+ clients using IPv4 mapped addresses.</TD></TR>
+ <TR>
+ <TH bgColor=#cccccc colSpan=3>Server specific options</TH></TR>
+ <TR vAlign=top>
+ <TD><A name=server></A><TT>-s, --server</TT></TD>
+ <TD><TT>$IPERF_SERVER</TT></TD>
+ <TD>Run Iperf in server mode.</TD></TR>
+ <TR>
+ <TD><TT>-D </TT> (from v1.2 or higher)</TD>
+ <TD>.</TD>
+ <TD>Run the server as a daemon (Unix platforms) <BR>On Win32 platforms
+ where services are available, Iperf will start running as a service.</TD></TR>
+ <TR>
+ <TD><TT>-R </TT>(only for Windows, from v1.2 or higher)</TD>
+ <TD>.</TD>
+ <TD>Remove the Iperf service (if it's running).&nbsp;</TD></TR><TR>
+ <TD><TT>-o </TT>(only for Windows, from v1.2 or higher)</TD>
+ <TD>.</TD>
+ <TD>Redirect output to given file.&nbsp;</TD></TR>
+ <TR vAlign=top>
+ <TD><A name=sclient></A><TT>-c, --client <I>host</I></TT></TD>
+ <TD><TT>$IPERF_CLIENT</TT></TD>
+ <TD> If Iperf is in server mode, then specifying a host with -c
+ will limit the connections that Iperf will accept to the
+ <I>host</I> specified. Does not work well for UDP.</TD></TR>
+ <TR vAlign=top>
+ <TD><A name=sparallel></A><TT>-P, --parallel <I>#</I></TT></TD>
+ <TD><TT>$IPERF_PARALLEL</TT></TD>
+ <TD>The number of connections to handle by the server before
+ closing. Default is 0 (which means to accept connections forever).</TD></TR>
+ <TR>
+ <TH bgColor=#cccccc colSpan=3>Client specific options</TH></TR>
+ <TR vAlign=top>
+ <TD><A name=bandwidth></A><TT>-b, --bandwidth <I>#[KM]</I></TT></TD>
+ <TD><TT>$IPERF_BANDWIDTH</TT></TD>
+ <TD>The UDP bandwidth to send at, in bits/sec. This implies the -u option.
+ Default is 1 Mbit/sec.</TD></TR>
+ <TR vAlign=top>
+ <TD><A name=client></A><TT>-c, --client <I>host</I></TT></TD>
+ <TD><TT>$IPERF_CLIENT</TT></TD>
+ <TD>Run Iperf in client mode, connecting to an Iperf server running on
+ <I>host</I>.</TD></TR>
+ <TR vAlign=top>
+ <TD><A name=dualtest></A><TT>-d, --dualtest </TT></TD>
+ <TD><TT>$IPERF_DUALTEST</TT></TD>
+ <TD>Run Iperf in dual testing mode. This will cause the server to connect
+ back to the client on the port specified in the
+ <A href="#listenport">-L</A> option (or defaults
+ to the port the client connected to the server on). This is done immediately
+ therefore running the tests simultaneously. If you want an alternating
+ test try <A href="#tradeoff">-r.</A></TD></TR>
+ <TR vAlign=top>
+ <TD><A name=num></A><TT>-n, --num <I>#[KM]</I></TT></TD>
+ <TD><TT>$IPERF_NUM</TT></TD>
+ <TD>The number of buffers to transmit. Normally, Iperf sends for 10
+ seconds. The -n option overrides this and sends an array of <I>len</I>
+ bytes <I>num</I> times, no matter how long that takes. See also the <A
+ href="#len">-l</A>
+ and <A
+ href="#time">-t</A>
+ options.</TD></TR>
+ <TR vAlign=top>
+ <TD><A name=tradeoff></A><TT>-r, --tradeoff </TT></TD>
+ <TD><TT>$IPERF_TRADEOFF</TT></TD>
+ <TD>Run Iperf in tradeoff testing mode. This will cause the server to connect
+ back to the client on the port specified in the
+ <A href="#listenport">-L</A> option (or defaults
+ to the port the client connected to the server on). This is done following
+ the client connection termination, therefore running the tests
+ alternating. If you want an simultaneous test try
+ <A href="#dualtest">-d.</A></TD></TR>
+ <TR vAlign=top>
+ <TD><A name=time></A><TT>-t, --time <I>#</I></TT></TD>
+ <TD><TT>$IPERF_TIME</TT></TD>
+ <TD>The time in seconds to transmit for. Iperf normally works by
+ repeatedly sending an array of <I>len</I> bytes for <I>time</I> seconds.
+ Default is 10 seconds. See also the <A
+ href="#len">-l</A>
+ and <A
+ href="#num">-n</A>
+ options.</TD></TR>
+ <TR vAlign=top>
+ <TD><A name=listenport></A><TT>-L, --listenport <I>#</I></TT></TD>
+ <TD><TT>$IPERF_LISTENPORT</TT></TD>
+ <TD>This specifies the port that the server will connect back to the
+ client on. It defaults to the port used to connect to the server
+ from the client.</TD></TR>
+ <TR vAlign=top>
+ <TD><A name=parallel></A><TT>-P, --parallel <I>#</I></TT></TD>
+ <TD><TT>$IPERF_PARALLEL</TT></TD>
+ <TD>The number of simultaneous connections to make to the server. Default
+ is 1. Requires thread support on both the client and server.</TD></TR>
+ <TR vAlign=top>
+ <TD><A name=tos></A><TT>-S, --tos <I>#</I></TT></TD>
+ <TD><TT>$IPERF_TOS</TT></TD>
+ <TD>The type-of-service for outgoing packets. (Many routers ignore the TOS
+ field.) You may specify the value in hex with a '0x' prefix, in octal with
+ a '0' prefix, or in decimal. For example, '0x10' hex = '020' octal = '16'
+ decimal. The TOS numbers specified in RFC 1349 are:&nbsp;
+ <PRE>
+&nbsp;&nbsp;&nbsp; IPTOS_LOWDELAY&nbsp;&nbsp;&nbsp;&nbsp; minimize delay&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 0x10
+&nbsp;&nbsp;&nbsp; IPTOS_THROUGHPUT&nbsp;&nbsp; maximize throughput&nbsp;&nbsp; 0x08
+&nbsp;&nbsp;&nbsp; IPTOS_RELIABILITY&nbsp; maximize reliability&nbsp; 0x04
+&nbsp;&nbsp;&nbsp; IPTOS_LOWCOST&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; minimize cost&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 0x02
+&nbsp;&nbsp;&nbsp;&nbsp;
+ </PRE>
+ </TD></TR>
+ <TR vAlign=top>
+ <TD><A name=ttl></A><TT>-T, --ttl <I>#</I></TT></TD>
+ <TD><TT>$IPERF_TTL</TT></TD>
+ <TD>The time-to-live for outgoing multicast packets. This is essentially
+ the number of router hops to go through, and is also used for scoping.
+ Default is 1, link-local.</TD></TR>
+ <TR>
+ <TD><TT>-F</TT> (from v1.2 or higher)</TD>
+ <TD>.</TD>
+ <TD>Use a representative stream to measure bandwidth, e.g. :-&nbsp; <BR>$
+ iperf -c &lt;server address&gt; -F &lt;file-name&gt;</TD></TR>
+ <TR>
+ <TD><TT>-I </TT>(from v1.2 or higher)</TD>
+ <TD>.</TD>
+ <TD>Same as -F, input from stdin.</TD></TR>
+ <!-- <TR>
+ <TD><TT>-W </TT>(from v1.2 or higher)</TD>
+ <TD>.</TD>
+ <TD>Adaptive Window Sizes.
+ <BR>Use Iperf to suggest the best Window size for a connection. Iperf will start from a default window size and try to perform a search for the optimal window size</TD></TR>
+--> <TR>
+ <TH bgColor=#cccccc colSpan=3>Miscellaneous options</TH></TR>
+ <TR vAlign=top>
+ <TD><A name=help></A><TT>-h, --help</TT></TD>
+ <TD>&nbsp;</TD>
+ <TD>Print out a summary of commands and quit.</TD></TR>
+ <TR vAlign=top>
+ <TD><A name=version></A><TT>-v, --version</TT></TD>
+ <TD>&nbsp;</TD>
+ <TD>Print version information and quit. Prints 'pthreads' if compiled with
+ POSIX threads, 'win32 threads' if compiled with Microsoft Win32 threads,
+ or 'single threaded' if compiled without threads.</TD></TR></TBODY></TABLE>
+<P>
+<HR>
+<!-- ----- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- -->
+<H2><A name=tuningtcp></A>Tuning a TCP connection</H2>
+
+The primary goal of Iperf
+is to help in tuning TCP connections over a particular path. The most
+fundamental tuning issue for TCP is the TCP window size, which controls how much
+data can be in the network at any one point. If it is too small, the sender will
+be idle at times and get poor performance. The theoretical value to use for the
+TCP window size is the <I>bandwidth delay product</I>,
+<BLOCKQUOTE>bottleneck bandwidth * round trip time</BLOCKQUOTE>In the below
+modi4/cyclops example, the bottleneck link is a 45 Mbit/sec DS3 link and the
+round trip time measured with ping is 42 ms. The bandwidth delay product is
+<BLOCKQUOTE>45 Mbit/sec * 42 ms <BR>= (45e6) * (42e-3) <BR>= 1890000 bits
+ <BR>= 230 KByte</BLOCKQUOTE>That is a starting point for figuring the best
+window size; setting it higher or lower may produce better results. In our
+example, buffer sizes over 130K did not improve the performance, despite the
+bandwidth delay product of 230K.
+<P>Note that many OSes and hosts have upper limits on the TCP window size. These
+may be as low as 64 KB, or as high as several MB. Iperf tries to detect when
+these occur and give a warning that the actual and requested window sizes are
+not equal (as below, though that is due to rounding in IRIX). PSC has a <A
+href="http://www.psc.edu/networking/perf_tune.html">list detailing</A> how to
+change the default and maximum window sizes for various OSes. For more
+information on TCP window sizes, see the <A
+href="http://dast.nlanr.net/Guides/GettingStarted/TCP_window_size.html">User's
+Guide to TCP Windows.</A>
+<P>Here is an example session, between node1 in Illinois and node2 in North
+Carolina. These are connected via the vBNS backbone and a 45 Mbit/sec DS3 link.
+Notice we improve bandwidth performance by a factor of 3 using proper TCP window
+sizes. Use the adaptive window sizes feature on platforms which allow setting
+window sizes in the granularity of bytes.
+<BLOCKQUOTE>
+<PRE>
+<B>node2&gt;</B> iperf -s
+------------------------------------------------------------
+Server listening on TCP port 5001
+TCP window size: 60.0 KByte (default)
+------------------------------------------------------------
+[&nbsp; 4] local &lt;IP Addr node2&gt; port 5001 connected with &lt;IP Addr node1&gt; port 2357
+[ ID] Interval&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Transfer&nbsp;&nbsp;&nbsp;&nbsp; Bandwidth
+[&nbsp; 4]&nbsp; 0.0-10.1 sec&nbsp;&nbsp; 6.5 MBytes&nbsp;&nbsp; <B><FONT color=#ff0000>5.2 Mbits/sec
+
+</FONT>node1&gt;</B> iperf -c node2
+------------------------------------------------------------
+Client connecting to node1, TCP port 5001
+TCP window size: 59.9 KByte (default)
+------------------------------------------------------------
+[&nbsp; 3] local &lt;IP Addr node1&gt; port 2357 connected with &lt;IP Addr node2&gt; port 5001
+[ ID] Interval&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Transfer&nbsp;&nbsp;&nbsp;&nbsp; Bandwidth
+[&nbsp; 3]&nbsp; 0.0-10.0 sec&nbsp;&nbsp; 6.5 MBytes&nbsp;&nbsp; 5.2 Mbits/sec</PRE>
+ <HR>
+<PRE><B>node2&gt;</B> iperf -s -w 130k
+------------------------------------------------------------
+Server listening on TCP port 5001
+TCP window size:&nbsp; 130 KByte
+------------------------------------------------------------
+[&nbsp; 4] local &lt;IP Addr node 2&gt; port 5001 connected with &lt;IP Addr node 1&gt; port 2530
+[ ID] Interval&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Transfer&nbsp;&nbsp;&nbsp;&nbsp; Bandwidth
+[&nbsp; 4]&nbsp; 0.0-10.1 sec&nbsp; 19.7 MBytes&nbsp; <B><FONT color=#ff0000>15.7 Mbits/sec
+
+</FONT>node1&gt;</B> iperf -c node2 -w 130k
+------------------------------------------------------------
+Client connecting to node2, TCP port 5001
+TCP window size:&nbsp; 129 KByte (WARNING: requested&nbsp; 130 KByte)
+------------------------------------------------------------
+[&nbsp; 3] local &lt;IP Addr node1&gt; port 2530 connected with &lt;IP Addr node2&gt; port 5001
+[ ID] Interval&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Transfer&nbsp;&nbsp;&nbsp;&nbsp; Bandwidth
+[&nbsp; 3]&nbsp; 0.0-10.0 sec&nbsp; 19.7 MBytes&nbsp; 15.8 Mbits/sec</PRE></BLOCKQUOTE>Another
+test to do is run parallel TCP streams. If the total aggregate bandwidth is more
+than what an individual stream gets, something is wrong. Either the TCP window
+size is too small, or the OS's TCP implementation has bugs, or the network
+itself has deficiencies. See above for TCP window sizes; otherwise diagnosing
+which is somewhat difficult. If Iperf is compiled with pthreads, a single client
+and server can test this, otherwise setup multiple clients and servers on
+different ports. Here's an example where a single stream gets 16.5 Mbit/sec, but
+two parallel streams together get 16.7 + 9.4 = 26.1 Mbit/sec, even when using
+large TCP window sizes:
+<BLOCKQUOTE><PRE><B>node2&gt;</B> iperf -s -w 300k
+------------------------------------------------------------
+Server listening on TCP port 5001
+TCP window size:&nbsp; 300 KByte
+------------------------------------------------------------
+[&nbsp; 4] local &lt;IP Addr node2&gt; port 5001 connected with &lt;IP Addr node1&gt; port 6902
+[ ID] Interval&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Transfer&nbsp;&nbsp;&nbsp;&nbsp; Bandwidth
+[&nbsp; 4]&nbsp; 0.0-10.2 sec&nbsp; 20.9 MBytes&nbsp; <B><FONT color=#ff0000>16.5 Mbits/sec
+
+</FONT></B>[&nbsp; 4] local &lt;IP Addr node2&gt; port 5001 connected with &lt;IP Addr node1&gt; port 6911
+[&nbsp; 5] local &lt;IP Addr node2&gt; port 5001 connected with &lt;IP Addr node2&gt; port 6912
+[ ID] Interval&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Transfer&nbsp;&nbsp;&nbsp;&nbsp; Bandwidth
+[&nbsp; 5]&nbsp; 0.0-10.1 sec&nbsp; 21.0 MBytes&nbsp; <B><FONT color=#ff0000>16.7 Mbits/sec
+</FONT></B>[&nbsp; 4]&nbsp; 0.0-10.3 sec&nbsp; 12.0 MBytes&nbsp;&nbsp;<B><FONT color=#ff0000> 9.4 Mbits/sec
+
+</FONT>node1&gt;</B> ./iperf -c node2 -w 300k
+------------------------------------------------------------
+Client connecting to node2, TCP port 5001
+TCP window size:&nbsp; 299 KByte (WARNING: requested&nbsp; 300 KByte)
+------------------------------------------------------------
+[&nbsp; 3] local &lt;IP Addr node2&gt; port 6902 connected with &lt;IP Addr node1&gt; port 5001
+[ ID] Interval&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Transfer&nbsp;&nbsp;&nbsp;&nbsp; Bandwidth
+[&nbsp; 3]&nbsp; 0.0-10.2 sec&nbsp; 20.9 MBytes&nbsp; 16.4 Mbits/sec
+
+<B>node1&gt;</B> iperf -c node2 -w 300k -P 2
+------------------------------------------------------------
+Client connecting to node2, TCP port 5001
+TCP window size:&nbsp; 299 KByte (WARNING: requested&nbsp; 300 KByte)
+------------------------------------------------------------
+[&nbsp; 4] local &lt;IP Addr node2&gt; port 6912 connected with &lt;IP Addr node1&gt; port 5001
+[&nbsp; 3] local &lt;IP Addr node2&gt; port 6911 connected with &lt;IP Addr node1&gt; port 5001
+[ ID] Interval&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Transfer&nbsp;&nbsp;&nbsp;&nbsp; Bandwidth
+[&nbsp; 4]&nbsp; 0.0-10.1 sec&nbsp; 21.0 MBytes&nbsp; 16.6 Mbits/sec
+[&nbsp; 3]&nbsp; 0.0-10.2 sec&nbsp; 12.0 MBytes&nbsp;&nbsp; 9.4 Mbits/sec</PRE></BLOCKQUOTE>A
+secondary tuning issue for TCP is the maximum transmission unit (MTU). To be
+most effective, both hosts should support Path MTU Discovery. PSC has a <A
+href="http://www.psc.edu/networking/perf_tune.html">list detailing</A> what OSes
+support Path MTU Discovery. Hosts without Path MTU Discovery often use 536 as
+the MSS, which wastes bandwidth and processing time. Use the -m option to
+display what MSS is being used, and see if this matches what you expect. Often
+it is around 1460 bytes for ethernet.
+<BLOCKQUOTE><PRE><B>node3&gt;</B> iperf -s -m
+------------------------------------------------------------
+Server listening on TCP port 5001
+TCP window size: 60.0 KByte (default)
+------------------------------------------------------------
+[&nbsp; 4] local &lt;IP Addr node3&gt; port 5001 connected with &lt;IP Addr node4&gt; port 1096
+[ ID] Interval&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Transfer&nbsp;&nbsp;&nbsp;&nbsp; Bandwidth
+[&nbsp; 4]&nbsp; 0.0- 2.0 sec&nbsp;&nbsp; 1.8 MBytes&nbsp;&nbsp; 6.9 Mbits/sec
+[&nbsp; 4] <B><FONT color=#ff0000>MSS size 1448 bytes (MTU 1500 bytes, ethernet)
+</FONT></B>[&nbsp; 4] Read lengths occurring in more than 5% of reads:
+[&nbsp; 4]&nbsp;&nbsp; 952 bytes read&nbsp;&nbsp; 219 times (16.2%)
+[&nbsp; 4]&nbsp; 1448 bytes read&nbsp; 1128 times (83.6%)</PRE></BLOCKQUOTE>Here
+is a host that doesn't support Path MTU Discovery. It will only send and receive
+small 576 byte packets.
+<BLOCKQUOTE><PRE><B>node4&gt;</B> iperf -s -m
+------------------------------------------------------------
+Server listening on TCP port 5001
+TCP window size: 32.0 KByte (default)
+------------------------------------------------------------
+[&nbsp; 4] local &lt;IP Addr node4&gt; port 5001 connected with &lt;IP Addr node3&gt; port 13914
+[ ID] Interval&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Transfer&nbsp;&nbsp;&nbsp;&nbsp; Bandwidth
+[&nbsp; 4]&nbsp; 0.0- 2.3 sec&nbsp;&nbsp; 632 KBytes&nbsp;&nbsp; 2.1 Mbits/sec
+<B><FONT color=#ff0000>WARNING: Path MTU Discovery may not be enabled.
+</FONT></B>[&nbsp; 4] <B><FONT color=#ff0000>MSS size 536 bytes (MTU 576 bytes, minimum)
+</FONT></B>[&nbsp; 4] Read lengths occurring in more than 5% of reads:
+[&nbsp; 4]&nbsp;&nbsp; 536 bytes read&nbsp;&nbsp; 308 times (58.4%)
+[&nbsp; 4]&nbsp; 1072 bytes read&nbsp;&nbsp;&nbsp; 91 times (17.3%)
+[&nbsp; 4]&nbsp; 1608 bytes read&nbsp;&nbsp;&nbsp; 29 times (5.5%)</PRE></BLOCKQUOTE>Iperf
+supports other tuning options, which were added for exceptional network
+situations like HIPPI-to-HIPPI over ATM. <BR>
+<HR>
+<!-- ----- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- -->
+
+<H2><A name=tuningudp></A>Tuning a UDP connection</H2>
+
+Iperf creates a constant bit rate UDP stream. This is a very artificial
+stream, similar to voice communication but not much else.
+<P>
+
+You will want to adjust the datagram size (-l) to the size your application
+uses.
+<P>
+
+The server detects UDP datagram loss by ID numbers in the datagrams. Usually
+a UDP datagram becomes several IP packets. Losing a single IP packet will lose
+the entire datagram. To measure packet loss instead of datagram loss, make the
+datagrams small enough to fit into a single packet, using the -l option. The
+default size of 1470 bytes works for ethernet. Out-of-order packets are also
+detected. (Out-of-order packets cause some ambiguity in the lost packet count;
+Iperf assumes they are not duplicate packets, so they are excluded from the lost
+packet count.) Since TCP does not report loss to the user, I find UDP tests
+helpful to see packet loss along a path.
+<P>
+
+Jitter calculations are continuously computed by the server, as specified by
+RTP in RFC 1889. The client records a 64 bit second/microsecond timestamp in the
+packet. The server computes the relative transit time as (server's receive time
+- client's send time). The client's and server's clocks do not need to be
+synchronized; any difference is subtracted out in the jitter calculation. Jitter
+is the smoothed mean of differences between consecutive transit times.
+<BLOCKQUOTE><PRE><B>node2&gt;</B> iperf -s -u -i 1
+------------------------------------------------------------
+Server listening on UDP port 5001
+Receiving 1470 byte datagrams
+UDP buffer size: 60.0 KByte (default)
+------------------------------------------------------------
+[&nbsp; 4] local &lt;IP Addr node2&gt; port 5001 connected with &lt;IP Addr node1&gt; port 9726
+[ ID] Interval&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Transfer&nbsp;&nbsp;&nbsp;&nbsp; Bandwidth&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Jitter&nbsp;&nbsp; Lost/Total Datagrams
+[&nbsp; 4]&nbsp; 0.0- 1.0 sec&nbsp;&nbsp; 1.3 MBytes&nbsp; 10.0 Mbits/sec&nbsp; 0.209 ms&nbsp;&nbsp;&nbsp; 1/&nbsp; 894 (0.11%)
+[&nbsp; 4]&nbsp; 1.0- 2.0 sec&nbsp;&nbsp; 1.3 MBytes&nbsp; 10.0 Mbits/sec&nbsp; 0.221 ms&nbsp;&nbsp;&nbsp; 0/&nbsp; 892 (0%)
+[&nbsp; 4]&nbsp; 2.0- 3.0 sec&nbsp;&nbsp; 1.3 MBytes&nbsp; 10.0 Mbits/sec&nbsp; 0.277 ms&nbsp;&nbsp;&nbsp; 0/&nbsp; 892 (0%)
+[&nbsp; 4]&nbsp; 3.0- 4.0 sec&nbsp;&nbsp; 1.3 MBytes&nbsp; 10.0 Mbits/sec&nbsp; 0.359 ms&nbsp;&nbsp;&nbsp; 0/&nbsp; 893 (0%)
+[&nbsp; 4]&nbsp; 4.0- 5.0 sec&nbsp;&nbsp; 1.3 MBytes&nbsp; 10.0 Mbits/sec&nbsp; 0.251 ms&nbsp;&nbsp;&nbsp; 0/&nbsp; 892 (0%)
+[&nbsp; 4]&nbsp; 5.0- 6.0 sec&nbsp;&nbsp; 1.3 MBytes&nbsp; 10.0 Mbits/sec&nbsp; 0.215 ms&nbsp;&nbsp;&nbsp; 0/&nbsp; 892 (0%)
+[&nbsp; 4]&nbsp; 6.0- 7.0 sec&nbsp;&nbsp; 1.3 MBytes&nbsp; 10.0 Mbits/sec&nbsp; 0.325 ms&nbsp;&nbsp;&nbsp; 0/&nbsp; 892 (0%)
+[&nbsp; 4]&nbsp; 7.0- 8.0 sec&nbsp;&nbsp; 1.3 MBytes&nbsp; 10.0 Mbits/sec&nbsp; 0.254 ms&nbsp;&nbsp;&nbsp; 0/&nbsp; 892 (0%)
+[&nbsp; 4]&nbsp; 8.0- 9.0 sec&nbsp;&nbsp; 1.3 MBytes&nbsp; 10.0 Mbits/sec&nbsp; 0.282 ms&nbsp;&nbsp;&nbsp; 0/&nbsp; 892 (0%)
+[&nbsp; 4]&nbsp; 0.0-10.0 sec&nbsp; 12.5 MBytes&nbsp; 10.0 Mbits/sec&nbsp; 0.243 ms&nbsp;&nbsp;&nbsp; 1/ 8922 (0.011%)
+
+<B>node1&gt;</B> iperf -c node2 -u -b 10m
+------------------------------------------------------------
+Client connecting to node2, UDP port 5001
+Sending 1470 byte datagrams
+UDP buffer size: 60.0 KByte (default)
+------------------------------------------------------------
+[&nbsp; 3] local &lt;IP Addr node1&gt; port 9726 connected with &lt;IP Addr node2&gt; port 5001
+[ ID] Interval&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Transfer&nbsp;&nbsp;&nbsp;&nbsp; Bandwidth
+[&nbsp; 3]&nbsp; 0.0-10.0 sec&nbsp; 12.5 MBytes&nbsp; 10.0 Mbits/sec
+[&nbsp; 3] Sent 8922 datagrams</PRE></BLOCKQUOTE>Notice the higher jitter due to
+datagram reassembly when using larger 32 KB datagrams, each split into 23
+packets of 1500 bytes. The higher datagram loss seen here may be due to the
+burstiness of the traffic, which is 23 back-to-back packets and then a long
+pause, rather than evenly spaced individual packets.
+<BLOCKQUOTE><PRE><B>node2&gt;</B> iperf -s -u -l 32k -w 128k -i 1
+------------------------------------------------------------
+Server listening on UDP port 5001
+Receiving 32768 byte datagrams
+UDP buffer size:&nbsp; 128 KByte
+------------------------------------------------------------
+[&nbsp; 3] local &lt;IP Addr node2&gt; port 5001 connected with &lt;IP Addr node1&gt; port 11303
+[ ID] Interval&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Transfer&nbsp;&nbsp;&nbsp;&nbsp; Bandwidth&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Jitter&nbsp;&nbsp; Lost/Total Datagrams
+[&nbsp; 3]&nbsp; 0.0- 1.0 sec&nbsp;&nbsp; 1.3 MBytes&nbsp; 10.0 Mbits/sec&nbsp; 0.430 ms&nbsp;&nbsp;&nbsp; 0/&nbsp;&nbsp; 41 (0%)
+[&nbsp; 3]&nbsp; 1.0- 2.0 sec&nbsp;&nbsp; 1.1 MBytes&nbsp;&nbsp; 8.5 Mbits/sec&nbsp; 5.996 ms&nbsp;&nbsp;&nbsp; 6/&nbsp;&nbsp; 40 (15%)
+[&nbsp; 3]&nbsp; 2.0- 3.0 sec&nbsp;&nbsp; 1.2 MBytes&nbsp;&nbsp; 9.7 Mbits/sec&nbsp; 0.796 ms&nbsp;&nbsp;&nbsp; 1/&nbsp;&nbsp; 40 (2.5%)
+[&nbsp; 3]&nbsp; 3.0- 4.0 sec&nbsp;&nbsp; 1.2 MBytes&nbsp; 10.0 Mbits/sec&nbsp; 0.403 ms&nbsp;&nbsp;&nbsp; 0/&nbsp;&nbsp; 40 (0%)
+[&nbsp; 3]&nbsp; 4.0- 5.0 sec&nbsp;&nbsp; 1.2 MBytes&nbsp; 10.0 Mbits/sec&nbsp; 0.448 ms&nbsp;&nbsp;&nbsp; 0/&nbsp;&nbsp; 40 (0%)
+[&nbsp; 3]&nbsp; 5.0- 6.0 sec&nbsp;&nbsp; 1.2 MBytes&nbsp; 10.0 Mbits/sec&nbsp; 0.464 ms&nbsp;&nbsp;&nbsp; 0/&nbsp;&nbsp; 40 (0%)
+[&nbsp; 3]&nbsp; 6.0- 7.0 sec&nbsp;&nbsp; 1.2 MBytes&nbsp; 10.0 Mbits/sec&nbsp; 0.442 ms&nbsp;&nbsp;&nbsp; 0/&nbsp;&nbsp; 40 (0%)
+[&nbsp; 3]&nbsp; 7.0- 8.0 sec&nbsp;&nbsp; 1.2 MBytes&nbsp; 10.0 Mbits/sec&nbsp; 0.342 ms&nbsp;&nbsp;&nbsp; 0/&nbsp;&nbsp; 40 (0%)
+[&nbsp; 3]&nbsp; 8.0- 9.0 sec&nbsp;&nbsp; 1.2 MBytes&nbsp; 10.0 Mbits/sec&nbsp; 0.431 ms&nbsp;&nbsp;&nbsp; 0/&nbsp;&nbsp; 40 (0%)
+[&nbsp; 3]&nbsp; 9.0-10.0 sec&nbsp;&nbsp; 1.2 MBytes&nbsp; 10.0 Mbits/sec&nbsp; 0.407 ms&nbsp;&nbsp;&nbsp; 0/&nbsp;&nbsp; 40 (0%)
+[&nbsp; 3]&nbsp; 0.0-10.0 sec&nbsp; 12.3 MBytes&nbsp;&nbsp; 9.8 Mbits/sec&nbsp; 0.407 ms&nbsp;&nbsp;&nbsp; 7/&nbsp; 401 (1.7%)
+
+<B>node1&gt;</B> iperf -c node2 -b 10m -l 32k -w 128k
+------------------------------------------------------------
+Client connecting to node2, UDP port 5001
+Sending 32768 byte datagrams
+UDP buffer size:&nbsp; 128 KByte
+------------------------------------------------------------
+[&nbsp; 3] local &lt;IP Addr node2&gt; port 11303 connected with &lt;IP Addr node1&gt; port 5001
+[ ID] Interval&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Transfer&nbsp;&nbsp;&nbsp;&nbsp; Bandwidth
+[&nbsp; 3]&nbsp; 0.0-10.0 sec&nbsp; 12.5 MBytes&nbsp; 10.0 Mbits/sec
+[&nbsp; 3] Sent 401 datagrams</PRE><PRE></PRE></BLOCKQUOTE>
+<P><A name=multicast></A>
+<B><FONT size=+1>Multicast</FONT></B>
+<P>To test multicast, run several servers with the bind option (-B, --bind) set
+to the multicast group address. Run the client, connecting to the multicast
+group address and setting the TTL (-T, --ttl) as needed. Unlike normal TCP and
+UDP tests, multicast servers may be started after the client. In that case,
+datagrams sent before the server started show up as losses in the first periodic
+report (61 datagrams on arno below).
+<BLOCKQUOTE><PRE><B>node5&gt;</B> iperf -c 224.0.67.67 -u --ttl 5 -t 5
+------------------------------------------------------------
+Client connecting to 224.0.67.67, UDP port 5001
+Sending 1470 byte datagrams
+Setting multicast TTL to 5
+UDP buffer size: 32.0 KByte (default)
+------------------------------------------------------------
+[&nbsp; 3] local &lt;IP Addr node5&gt; port 1025 connected with 224.0.67.67 port 5001
+[ ID] Interval&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Transfer&nbsp;&nbsp;&nbsp;&nbsp; Bandwidth
+[&nbsp; 3]&nbsp; 0.0- 5.0 sec&nbsp;&nbsp; 642 KBytes&nbsp;&nbsp; 1.0 Mbits/sec
+[&nbsp; 3] Sent 447 datagrams
+
+<B>node5&gt;</B> iperf -s -u -B 224.0.67.67 -i 1
+------------------------------------------------------------
+Server listening on UDP port 5001
+Binding to local address 224.0.67.67
+Joining multicast group&nbsp; 224.0.67.67
+Receiving 1470 byte datagrams
+UDP buffer size: 32.0 KByte (default)
+------------------------------------------------------------
+[&nbsp; 3] local 224.0.67.67 port 5001 connected with &lt;IP Addr node5&gt; port 1025
+[ ID] Interval&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Transfer&nbsp;&nbsp;&nbsp;&nbsp; Bandwidth&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Jitter&nbsp;&nbsp; Lost/Total Datagrams
+[&nbsp; 3]&nbsp; 0.0- 1.0 sec&nbsp;&nbsp; 131 KBytes&nbsp;&nbsp; 1.0 Mbits/sec&nbsp; 0.007 ms&nbsp;&nbsp;&nbsp; 0/&nbsp;&nbsp; 91 (0%)
+[&nbsp; 3]&nbsp; 1.0- 2.0 sec&nbsp;&nbsp; 128 KBytes&nbsp;&nbsp; 1.0 Mbits/sec&nbsp; 0.008 ms&nbsp;&nbsp;&nbsp; 0/&nbsp;&nbsp; 89 (0%)
+[&nbsp; 3]&nbsp; 2.0- 3.0 sec&nbsp;&nbsp; 128 KBytes&nbsp;&nbsp; 1.0 Mbits/sec&nbsp; 0.010 ms&nbsp;&nbsp;&nbsp; 0/&nbsp;&nbsp; 89 (0%)
+[&nbsp; 3]&nbsp; 3.0- 4.0 sec&nbsp;&nbsp; 128 KBytes&nbsp;&nbsp; 1.0 Mbits/sec&nbsp; 0.013 ms&nbsp;&nbsp;&nbsp; 0/&nbsp;&nbsp; 89 (0%)
+[&nbsp; 3]&nbsp; 4.0- 5.0 sec&nbsp;&nbsp; 128 KBytes&nbsp;&nbsp; 1.0 Mbits/sec&nbsp; 0.008 ms&nbsp;&nbsp;&nbsp; 0/&nbsp;&nbsp; 89 (0%)
+[&nbsp; 3]&nbsp; 0.0- 5.0 sec&nbsp;&nbsp; 642 KBytes&nbsp;&nbsp; 1.0 Mbits/sec&nbsp; 0.008 ms&nbsp;&nbsp;&nbsp; 0/&nbsp; 447 (0%)
+
+<B>node6&gt;</B> iperf -s -u -B 224.0.67.67 -i 1
+------------------------------------------------------------
+Server listening on UDP port 5001
+Binding to local address 224.0.67.67
+Joining multicast group&nbsp; 224.0.67.67
+Receiving 1470 byte datagrams
+UDP buffer size: 60.0 KByte (default)
+------------------------------------------------------------
+[&nbsp; 3] local 224.0.67.67 port 5001 connected with &lt;IP Addr node5&gt; port 1025
+[ ID] Interval&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Transfer&nbsp;&nbsp;&nbsp;&nbsp; Bandwidth&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Jitter&nbsp;&nbsp; Lost/Total Datagrams
+[&nbsp; 3]&nbsp; 0.0- 1.0 sec&nbsp;&nbsp; 129 KBytes&nbsp;&nbsp; 1.0 Mbits/sec&nbsp; 0.778 ms&nbsp;&nbsp; 61/&nbsp; 151 (40%)
+[&nbsp; 3]&nbsp; 1.0- 2.0 sec&nbsp;&nbsp; 128 KBytes&nbsp;&nbsp; 1.0 Mbits/sec&nbsp; 0.236 ms&nbsp;&nbsp;&nbsp; 0/&nbsp;&nbsp; 89 (0%)
+[&nbsp; 3]&nbsp; 2.0- 3.0 sec&nbsp;&nbsp; 128 KBytes&nbsp;&nbsp; 1.0 Mbits/sec&nbsp; 0.264 ms&nbsp;&nbsp;&nbsp; 0/&nbsp;&nbsp; 89 (0%)
+[&nbsp; 3]&nbsp; 3.0- 4.0 sec&nbsp;&nbsp; 128 KBytes&nbsp;&nbsp; 1.0 Mbits/sec&nbsp; 0.248 ms&nbsp;&nbsp;&nbsp; 0/&nbsp;&nbsp; 89 (0%)
+[&nbsp; 3]&nbsp; 0.0- 4.3 sec&nbsp;&nbsp; 554 KBytes&nbsp;&nbsp; 1.0 Mbits/sec&nbsp; 0.298 ms&nbsp;&nbsp; 61/&nbsp; 447 (14%)</PRE><PRE><HR width="100%"></PRE></BLOCKQUOTE>
+<P><A name=ipv6></A>
+<DL>
+ <DT><B><FONT size=+2>IPv6 Mode</FONT></B>
+ <DD>Download the IPv6 version of this release.<BR>Get the IPv6 address of the node using the 'ifconfig' command.<BR>Use the <FONT color=#000099>-V</FONT> option to indicate that you are using an IPv6 address Please note that we need to explicitly bind the server address also.
+ <P>Server side:<BR><FONT color=#000099> $ iperf -s -V</FONT>
+ <P>Client side:<BR><FONT color=#000099>$ iperf -c &lt;Server IPv6 Address&gt; -V </FONT>
+ <P>Note: Iperf version 1.6.2 and eariler require a IPv6 address to be explicitly bound
+ with the <A HREF="#bind">-B</A> option for the server.</P></DD></DL>
+<HR>
+<P><A name=repmode></A>
+<DL>
+ <DT><B><FONT size=+2>Using Representative Streams to measure
+ bandwidth</FONT></B>
+ <DD>Use the -F or -I option. If you want to test how your network performs
+ with compressed / uncompressed streams, just create representative streams and
+ use the -F option to test it. This is usually due to the link layer
+ compressing data.
+ <P>The -F option is for file input.<BR>The -I option is for input from stdin.
+ <P>E.g. <BR>Client: $ <FONT color=#000099> iperf -c &lt;server address&gt; -F &lt;file-name&gt;<BR></FONT>
+ <BR>Client: $ <FONT color=#000099> iperf -c &lt;server address&gt; -I </FONT></P></DD></DL>
+<P><A name=daemon></A>
+<HR>
+<DL>
+ <DT><B><FONT size=+2>Running the server as a daemon</FONT></B>
+ <DD>Use the -D command line option to run the server as a daemon. Redirect the
+ output to a file.<BR>E.g. <FONT color=#000099>iperf -s -D &gt;
+ iperfLog</FONT>. <FONT color=#000000>This will have the Iperf Server running
+ as a daemon and the server messages will be logged in the file iperfLog.
+</DD></DL>
+<HR>
+<P><A name=service></A>
+<DL>
+ <DT><B><FONT size=+2>Using Iperf as a Service under Win32</FONT></B>
+ <DD>There are three options for Win32:
+ <P>
+ <DL>
+ <DT>-o outputfilename
+ <DD>output the messages into the specified file
+ <DT>-s -D
+ <DD>install Iperf as a service and run it
+ <DT>-s -R
+ <DD>uninstall the Iperf service </DD></DL>
+ <P>Examples:
+ <DL>
+ <DT><FONT color=#3366ff>iperf -s -D -o iperflog.txt</FONT>
+ <DD>will install the Iperf service and run it. Messages will be reported
+ into "%windir%\system32\iperflog.txt"
+ <P></P>
+ <DT><FONT color=#3366ff>iperf -s -R</FONT>
+ <DD>will uninstall the Iperf service if it is installed.
+ <P>Note: If you stop want to restart the Iperf service after having killed
+ it with the Microsoft Management Console or the Windows Task Manager, make
+ sure to use the proper OPTION in the service properties dialog.
+ </P></DD></DL></DD></DL>
+<HR>
+<!--<P><A name=multicast></A>
+<DL>
+ <DT><B><FONT size=+2>Running the multicast server and client</FONT></B>
+ <DD>Use the -B option while starting the server to bind it to a multicast
+ address.<BR>E.g. :-<FONT color=#3366ff>iperf -s -u -B 224.0.55.55</FONT>.
+
+ <P>This will have the Iperf server listening for datagrams (-u) for the
+ address 224.0.55.55(-B 224.0.55.55).
+ <P>Now, start a client sending packets to this multicast address.
+ <P>E.g. : <FONT color=#3366ff>iperf -c 224.0.55.55 -u</FONT>.
+ This will have a UDP client (-u) sending to the multicast address
+ 224.0.55.55(-c 224.0.55.55).
+ <P><FONT color=#000000>Start multiple clients or servers as explained above,
+ sending data to the same multicast server. (If you have multiple servers
+ listening on the multicast address, each of the servers will be getting the data)
+</P></DD></DL>
+<HR>-->
+<!--<A name=adaptive></A>
+<DL>
+ <DT><B><FONT size=+2>Adaptive window sizes</FONT></B>
+ <DD>Use the -W option on the client to run the client with the adaptive window
+ size. Ensure that the server window size is fairly big for this
+ option.<BR>E.g.. If the server TCP window size is 8KB, it does not help having
+ a client TCP window size of 256KB.<BR>256KB Server TCP Window Size should
+ suffice for most high bandwidth networks.
+ <P>Client changes the TCP window size using a binary exponential
+ algorithm. This means that you may notice that TCP window size suggested may
+ vary according to the traffic in the network, Iperf will suggest the best
+ window size for the current network scenario.
+</DL>
+<HR width="100%">
+--><P><!-- ----- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- -->
+<CENTER>
+<P>Copyright 1999,2000,2001,2002,2003,2004 <BR>The Board of Trustees of the University of
+Illinois <BR>All rights reserved <BR>See <A
+href="ui_license.html">UI License</A> for
+complete details.</CENTER>
+</BODY>
+</HTML>
+