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Commit 9a8bb61f authored by Leigh B. Stoller's avatar Leigh B. Stoller

Add FAQ entries on plr and delay, as requested by Mike.

parent 77487dcf
......@@ -61,9 +61,6 @@
parameters on my links?</a>
<li> <a href="#HDS-7">Are there other traffic shaping parameters
besides latency, bandwidth, and PLR?</a>
<li> <a href="#HDS-8">I asked for traffic shaping, but everything
seems to be going at full LAN speeds.
What's wrong?</a>
</ul>
<li> <a href="#SWS">Software setup</a>
......@@ -91,7 +88,14 @@
<li> <a href="#TR">Troubleshooting</a>
<ul>
<li> <a href="#TR-1">My experiment is setup, but I cannot
send packets between some of the nodes, why?</a>
send packets between some of the nodes. Why?</a>
<li> <a href="#TR-2">I asked for traffic shaping, but everything
seems to be going at full LAN speeds.
What's wrong?</a>
<li> <a href="#TR-3">I set a non-zero packet-loss (or delay) but 'ping'
shows no packet-loss (or delay). Why?</a>
<li> <a href="#TR-4">I set a non-zero packet-loss (or delay) but 'ping'
shows a different packet-loss (or delay). Why?</a>
</ul>
</ul>
......@@ -788,37 +792,6 @@
sudo</a> command.
</p>
<li><a NAME="HDS-8"></a>
<h3>I asked for traffic shaping, but everything seems to be going at
full LAN speeds. What's wrong?</h3>
<p>
The most likely problem is that it is using the unshaped control
network for the traffic you're looking at. This occurs when it
tries to contact a node using a "pcXXX" address, like pc76 or
pc76.emulab.net, or when it tries to ping a fully-qualified name,
like NodeA.myexpt.myproj.emulab.net , which also resolves to a
control network address. On one of your nodes, take a look at the
file /etc/hosts . It shows the IP addresses and aliases that refer
to the different experimental interfaces. These are the names/IPs
you can use to see the delays.
</p>
<p>
For instance, let's say I have an experiment that had NodeA and
NodeB connected with a shaped link. The file /etc/hosts on NodeA
would have a line for NodeB, with an address like 192.168.1.3, and
on NodeB there would be an entry for NodeA with the address
192.168.1.2. These addresses correspond to the delayed link
between them. Any address outside the 192.168.*.* range that you
didn't configure manually corresponds to an unshaped link.
</p>
<p>
For a discussion of the way to 'name' interfaces on the control
and experimental networks, see the the <a href="#UTT-Naming">naming
section</a> of this document.
</p>
</ul>
<hr>
......@@ -1082,7 +1055,7 @@
<ul>
<li><a NAME="TR-1"></a>
<h3>My experiment is setup, but I cannot
send packets between some of the nodes, why?</h3>
send packets between some of the nodes. Why?</h3>
<p>
The most common reason is that your topology
includes nodes which are not directly connected, and you have
......@@ -1095,4 +1068,50 @@
duplex with the Cisco switch, or the physical wire is loose
or bad. In these cases, you should contact us for help.
</p>
<li><a NAME="TR-2"></a>
<h3>I asked for traffic shaping, but everything seems to be going at
full LAN speeds. What's wrong?</h3>
<p>
The most likely problem is that it is using the unshaped control
network for the traffic you're looking at. This occurs when it
tries to contact a node using a "pcXXX" address, like pc76 or
pc76.emulab.net, or when it tries to ping a fully-qualified name,
like NodeA.myexpt.myproj.emulab.net , which also resolves to a
control network address. On one of your nodes, take a look at the
file /etc/hosts . It shows the IP addresses and aliases that refer
to the different experimental interfaces. These are the names/IPs
you can use to see the delays.
</p>
<p>
For instance, let's say I have an experiment that had NodeA and
NodeB connected with a shaped link. The file /etc/hosts on NodeA
would have a line for NodeB, with an address like 192.168.1.3, and
on NodeB there would be an entry for NodeA with the address
192.168.1.2. These addresses correspond to the delayed link
between them. Any address outside the 192.168.*.* range that you
didn't configure manually corresponds to an unshaped link.
</p>
<p>
For a discussion of the way to 'name' interfaces on the control
and experimental networks, see the the <a href="#UTT-Naming">naming
section</a> of this document.
</p>
<li><a NAME="TR-3"></a>
<h3>I set a non-zero packet-loss (or delay) but 'ping'
shows no packet-loss (or delay). Why?</h3>
<p>
You are probably pinging through the control net interface. See this
Troubleshooting <a href="#TR-2">FAQ entry</a>.
</p>
<li><a NAME="TR-4"></a>
<h3>I set a non-zero packet-loss (or delay) but 'ping'
shows a different packet-loss (or delay). Why?</h3>
<p>
Ping is round trip, PLR and delay are "one way".
</p>
</ul>
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