-*/etc/rrqnet/ifupdown.sh* is a utility script for upholding +rrqnet+
-virtual cables via +/etc/network/interfaces+. The script is set up
-as both "pre-up" and "post-down" scripts for handling the associated
-+rrqnet+ configurations to bring up and tear down virtual cable plugs
-over +tap+ interfaces.
+*/etc/rrqnet/ifupdown.sh* is a utility script for managing +rrqnet+
+virtual cables via +/etc/network/interfaces+ declarations. In normal
+use the script is set up as "pre-up" and "post-down" scripts by means
+of links from +/etc/network/if-pre-up.d/rrqnet+ and from
++/etc/network/if-post-down.d/rrqnet+. It will then be invoked by
++ifup+ and +ifdown+ for handling the +rrqnet+ declarations and bring
+up or tear down +rrqnet+ virtual cable plugs over +tap+ interfaces.
+
+An +rrqnet+ virtual cable uses a +tap+ interface at each cable end
+host, and a service process (aptly named +rrqnet+) to tunnel the +tap+
+network traffic over UDP. Each +rrqnet+ process acts as a networking
+switch that facilitates level 2 connectivity among all its end points
+with packet routing according to the destination Ethernet machine
+addresses.
+
+This script handles the special purpose "option codes" for the IFACE
+stanzas that are used for declaring the +rrqnet+ daemon configuration
+to for the +tap+ interface for its virtual cabling. I.e., the IFACE
+stanza is made for the tap interface and it includes one or more of
+these +rrqnet+ options.
+
+The list of IFACE options for +rrqnet+ are: