Cisco 300 Series Cli Manual page 617

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assigned to the interface are set to a pending state. Duplicate address detection is
automatically restarted on an interface when the interface returns to being
administratively up.
An interface returning to administratively up, restarts duplicate address detection
for all of the Unicast IPv6 addresses on the interface. While duplicate address
detection is performed on the link-local address of an interface, the state for the
other IPv6 addresses is still set to TENTATIVE. When duplicate address detection
is completed on the link-local address, duplicate address detection is performed
on the remaining IPv6 addresses.
When duplicate address detection identifies a duplicate address, the state of the
address is set to DUPLICATE and the address is not used. If the duplicate address
is the link-local address of the interface, the processing of IPv6 packets is
disabled on the interface and an error SYSLOG message is issued.
If the duplicate address is a global address of the interface, the address is not
used and an error SYSLOG message is issued.
All configuration commands associated with the duplicate address remain as
configured while the state of the address is set to DUPLICATE.
If the link-local address for an interface changes, duplicate address detection is
performed on the new link-local address and all of the other IPv6 address
associated with the interface are regenerated (duplicate address detection is
performed only on the new link-local address).
Note. Since DAD is not supported on NBMA interfaces the command is allowed
but does not impact on an IPv6 tunnel interface of the ISATAP type it does not
impact. The configuration is saved and will impacted when the interface type is
changed on another type on which DAD is supported (for example, to the IPv6
manual tunnel).
Example
The following example configures five consecutive neighbor solicitation
messages to be sent on VLAN 1 while duplicate address detection is being
performed on the tentative Unicast IPv6 address of the interface. The example
also disables duplicate address detection processing on VLAN 2.
switchxxxxxx(config)#
switchxxxxxx(config-if)#
switchxxxxxx(config-if)#
switchxxxxxx(config)#
switchxxxxxx(config-if)#
interface vlan 1
ipv6 nd dad attempts 5
exit
interface vlan 2
ipv6 nd dad attempts 0
OL-32830-01 Command Line Interface Reference Guide
IPv6 Commands