Comment tweaks and additions.

mininet/net.py

@@ -14,6 +14,7 @@
 top of a single Linux kernel.
 
 Each host has:
+
 A virtual console (pipes to a shell)
 A virtual interfaces (half of a veth pair)
 A parent shell (and possibly some child processes) in a namespace

mininet/node.py

 #!/usr/bin/env python
-"Node objects for Mininet."
+
+"""
+Node objects for Mininet.
+
+Nodes provide a simple abstraction for interacting with
+hosts, switches and controllers. Local nodes are simply
+one or more processes on the local machine.
+
+Node: superclass for all (currently only local) network nodes.
+
+Host: a virtual host.
+
+Switch: superclass for switch nodes.
+
+UserSwitch: a switch using the user-space switch from the OpenFlow
+    reference implementation.
+
+KernelSwitch: a switch using the kernel switch from the OpenFlow reference
+    implementation.
+
+OVSSwitch: a switch using the OpenVSwitch OpenFlow-compatible switch
+    implementation (openvswitch.org).
+
+Controller: superclass for OpenFlow controllers. The default controller
+    is controller(8) from the reference implementation.
+
+NOXController: a controller node using NOX (noxrepo.org).
+
+RemoteController: a remote controller node, which may use any
+    arbitrary OpenFlow-compatible controller.
+"""
 
 from subprocess import Popen, PIPE, STDOUT
 import os

mininet/util.py

 #!/usr/bin/env python
+
 "Utility functions for Mininet."
 
 from time import sleep

mininet/xterm.py

@@ -2,9 +2,9 @@
 
 """
 XTerm creation and cleanup.
-Utility functions to run an xterm ( connected via screen( 1 ) ) on each host.
+Utility functions to run an xterm (connected via screen(1)) on each host.
 
-Requires xterm( 1 ) and GNU screen( 1 ).
+Requires xterm(1) and GNU screen(1).
 """
 
 import re