IPv6 Addressing Configuration
Duplicate Address Detection (DAD)
4-20
Operating Notes
A verified link-local unicast address must exist on a VLAN interface before
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the switch can run DAD on other addresses associated with the interface.
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If a previously configured unicast address is changed, a neighbor adver-
tisement (an all-nodes multicast message--ff02::1) is sent to notify other
devices on the VLAN and to perform duplicate address detection.
IPv6 addresses on a VLAN interface are assigned to multicast address
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groups identified with well- known prefixes. For more on this topic, refer
to "Multicast Application to IPv6 Addressing" on page 3-21.
DAD is performed on all stateful, stateless, and statically configured
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unicast addresses, but not on Anycast addresses.
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Neighbor solicitations for DAD do not cause the neighbor cache of
neighboring switches to be updated.
If a previously configured unicast address is changed, a neighbor adver-
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tisement is sent on the VLAN to notify other devices, and also for duplicate
address detection.
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If DAD is disabled when an address is configured, the address is assumed
to be unique and is assigned to the interface.