Enabling IPv6 on an Interface

device# configure terminal
device(config)# interface ethernet 1/1/1
device(config-if-e1000-1/1/1)# ipv6 enable

Note: In the preceding example, the interface is assigned an automatically computed link-local address. When configuring VLANs that share a common tagged interface with a physical or Virtual Ethernet (VE) interface, your should override the automatically computed link-local address with a manually configured unique address for the interface. If the interface uses the automatically computed address, which in the case of physical and VE interfaces is derived from a global MAC address, all physical and VE interfaces will have the same MAC address. To override a link-local address that is automatically computed for an interface with a manually configured address, refer to Configuring a link-local IPv6 address on an interface.