The destination address to be used for router
advertisements on this interface. If the value
of this object is 'multicast' (the default),
router advertisements sent on this interface will
be sent to the all-hosts multicast address, 224.0.0.1.
If the value of this object is 'broadcast',
router advertisements sent on this interface will
be sent to the limitied broadcast address,
255.255.255.255.