IPv6 Addressing
The Unspecified Address
The Unspecified Address
The “unspecified” address is defined as 0.0.0.0.0.0.0.0 (::/128, or just ::). It can
be used, for example, as a temporary source address in multicast traffic sent
by an interface that has not yet acquired its own address. The unspecified
address cannot be statically configured on the switch, or used as a destination
address.
IPv6 Address Deprecation
Preferred and Valid Address Lifetimes
Autoconfigured IPv6 global unicast addresses acquire their valid and
preferred lifetime assignments from router advertisements. A valid lifetime is
the time period during which an address is allowed to remain available and
usable on an interface. A preferred lifetime is the length of time an address is
intended for full use on an interface, and must be less than or equal to the
address's valid lifetime.
End of
Preferred
Lifetime
Address
Address “Preferred”
“Deprecated”
Valid Lifetime
Address
Address
Acquired
Removed
Figure 3-1. Valid and Preferred Lifetimes
When the preferred lifetime expires, the address becomes deprecated,
meaning that the address should no longer be used as a source address (except
for existing exchanges that began before the timeout occurred), but can still
be used as a destination. When the timeout arrives for the valid lifetime, the
address becomes unusable.
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