+ Key-value pairs for use by external frameworks that integrate
+ with Open vSwitch, rather than by Open vSwitch itself. System
+ integrators should either use the Open vSwitch development
+ mailing list to coordinate on common key-value definitions, or
+ choose key names that are likely to be unique. The currently
+ defined common key-value pairs are:
+ <dl>
+ <dt><code>attached-mac</code></dt>
+ <dd>
+ The MAC address programmed into the ``virtual hardware'' for this
+ interface, in the form
+ <var>xx</var>:<var>xx</var>:<var>xx</var>:<var>xx</var>:<var>xx</var>:<var>xx</var>.
+ For Citrix XenServer, this is the value of the <code>MAC</code>
+ field in the VIF record for this interface.</dd>
+ <dt><code>iface-id</code></dt>
+ <dd>A system-unique identifier for the interface. On XenServer,
+ this will commonly be the same as <code>xs-vif-uuid</code>.</dd>
+ </dl>