IPv6 Configuration Guide K/KA/KB.15.15

If default is used without the no-advertise, no-autoconfig, or the
off-link keyword, the advertisement setting for the absent keyword is
returned to its default setting.
NOTE: To configure a prefix as off-link or no-autoconfig , you must
enter unique valid and preferred lifetimes with the prefix command (instead
of the default command).
ipv6-prefix / prefix-len
Specifies the prefixes to advertise on the subject VLAN or tunnel. A separate
instance of the command must be used for each prefix to advertise.
infinite
Specifies that the prefix lifetime will not expire. This option sets the valid and
preferred lifetimes to infinity. (All bits set to 1; ffffffff.)
no-advertise
Specifies no advertisement for the prefix.
For example, if the routing-switches VLAN or tunnel interface is configured with
any prefixes that you do not want advertised on the VLAN, use this command
to specify the prefixes to withhold from advertisements on the subject VLAN or
tunnel.
Default: Advertising enabled.
no-autoconfig
Disables host autoconfiguration by turning off the A-bit in RAs. This requires
hosts to acquire prefixes through manual or DHCPv6 assignments. Depending
on the host implementation, a host that was previously configured by an RA to
use autoconfiguration will not be affected by a later RA that includes
no-autoconfig (unless the host disconnects and reconnects to the network).
To re-enable host autoconfiguration (turn on the A-bit in RAs) for a given RA,
use ipv6 nd ra prefix again, without invoking no-autoconfig.
Default: A-bit turned on— host autoconfig turned on.
off-link
Sets the (L-bit) prefix information in an RA to indicate that the advertised prefix
is not on the subject VLAN. A host that was previously configured using an RA
without off-link will not be affected by a later RA that includes off-link
(unless the host disconnects and reconnects to the network).
Can be used in instances where the prefix is being deprecated, and you do
not want any newly brought up hosts to use the prefix.
Default: L-bit turned off.
The no form of the command deletes the specified prefix from RAs.
VLAN or tunnel context ND configuration 191