IPv6 - enabling on a shutdown interface

When configuring IPv6 on a Cisco router, ensure that the interface is enabled using the no shutdown command. If the interface is not up, you may encounter the error message

IPv6 isn't enabled on this interface.

To verify the status, use the show ipv6 interface brief command to check if the interface has a link-local address assigned. If the interface is down, it will not have IPv6 enabled.

Additional information can be found at IPv6 - understanding how to enable IPv6 functionality and routing on an IOS device.