First, we need to enable IPv6 routing on a Cisco router using the ipv6 unicast-routing global configuration command because Cisco routers do not have IPv6 routing enabled by default. This command globally enables IPv6 and must be the first command executed on the router.

Then configure IPv6 global unicast address on an interface using the ipv6 address <address>/prefix-length [eui-64] command. After you enter this command, the link-local address will be automatically derived.

We can configure the entire address manually by omitting the eui-64 parameter.

Follow the steps given below:

R1(config)#ipv6 unicast-routing

R1(config)#interface Fastethernet0/0

R1(config-if)#ipv6 address 2001:0BB9:AABB:1234::/64 eui-64

We can verify that the IPv6 address has been configured by using the command:

R1#show ipv6 interface Fa0/0