KB.15.15

Where a static link-local address is already configured, a new, autoconfigured

global unicast addresses assignment uses the same interface identifier as the

link-local address.

NOTE: An existing link-local address is replaced, and is not deprecated, when

a static replacement is configured.

The prefix for a statically configured link-local address is always 64 bits, with all

blocks after fe80 set to zero. That is: fe80:0:0:0.

After verification of uniqueness by DAD, a statically configured link-local address

status is set to preferred, with a permanent lifetime.

For link-local addressing, the [no] form of the static IPv6 address command

produces different results, depending on how IPv6 is configured on the VLAN:

• If IPv6 was enabled only by a statically configured link-local address, deleting

the link-local address disables IPv6 on the VLAN.

• If other IPv6-enabling commands have been configured on the VLAN, deleting

the statically configured link-local address causes the switch to replace it with

the default (EUI-64) link-local address for the VLAN, and IPv6 remains enabled.

See also “About disabling IPv6 on a VLAN” (page 30).

Statically configuring a global unicast address

Syntax:

[no] ipv6 address [ network-prefix interface-id/prefix-length ]

[no] ipv6 address [ network-prefix::/prefix-length ]

eui-64

If IPv6 is not already enabled on a VLAN, either of these command options do the

following:

• Enable IPv6 on the VLAN

• Configure a link-local address using the EUI-64 format

• Statically configure a global unicast address

If IPv6 is already enabled on the VLAN, the above commands statically configure

a global unicast address, but have no effect on the current link-local address.

network-prefix

This includes the global routing prefix and the subnet ID for the address.

interface-id

Enters a user-defined interface identity.

prefix-length

Specifies the number of bits in the network prefix. If you are using the eui-64

option, this value must be 64.

eui-64

Specifies using the EUI format to create an interface identifier based on the

VLAN MAC address.

After verification of uniqueness by DAD, the lifetime of a statically configured IPv6

address assigned to a VLAN is set to permanent and is configured as a preferred

address.

The [no] form of the command erases the specified address and, if no other

IPv6-enabling command is configured on the VLAN, disables IPv6 on the VLAN.

Statically configuring a global unicast address 19