Commit 8715f4cb authored by Leigh B. Stoller's avatar Leigh B. Stoller

Add FAQ entry for changing other traffic shaping parameters that are

not supported in the front end.
parent 6c9f72bd
......@@ -50,6 +50,8 @@
<li> <a href="#HDS-5">Can I do traffic shaping on my links?</a>
<li> <a href="#HDS-6">Can I modify the traffic shapping
parameters on my links?</a>
<li> <a href="#HDS-7">Are there other traffic shapping parameters
besides latency, bandwidth, and PLR?</a>
</ul>
<li> <a href="#SWS">Software setup</a>
......@@ -444,6 +446,33 @@
page. The command line syntax for <tt>delay_config</tt> will be
displayed when the <tt>-h</tt> option is given.
</p>
<li><a NAME="HDS-7"></a>
<h3>Are there other traffic shapping parameters besides latency,
bandwidth, and packet loss rate?</h3>
<p>
Yes! However, access to those other parameters is slightly more
difficult since you cannot specify them in your NS file. First
off, you should log into <tt>users.emulab.net</tt> and read the
man page for
<a href='http://www.freebsd.org/cgi/man.cgi?manpath=FreeBSD+4.3-RELEASE'>
<tt>ipfw</tt></a>. Refer to the section on <tt>dummynet</tt>; ipfw
is the user interface for the <tt>Dummynet</tt> traffic shaper.
As noted in previous section above, you can alter the traffic
shapping parameters of any delayed link (one in which you have
specified a bandwidth, delay, or PLR that causes a delay node to
be inserted). However, you will need to log into the delay node
for the link you wish to modify and interact with <tt>ipfw</tt>
directly. The easiest approach would be to make a copy of
</tt>/etc/testbed/rc.delay</tt> and edit the pipe commands as
desired (or replace the pipe commands with "queue" commands). The
pipe commands are indexed by number; the mapping from pipe number
to virtual link is available via the web interface on the
Experiment Information page for your experiment. Be sure to leave
the rest of the contents of the file as is. Once you have your
changes made, simply execute the file using the <a href="#UTT-2">
sudo</a> command.
</p>
</ul>
<hr>
......
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