doesn't sound like a benefit. I believe that it is, though. All the control freaks out there (like me) who like to make your router the first or last IP address on your network are out of luck now. Whatever shall we do? We will do what we should have been doing all along-using DNS to name our addresses. If the adoption of IPv6 does nothing but force everyone to properly use DNS, I will consider it a success. OK, SO you're too much of a control freak and you simply must manually configure your devices. Of course, you can. Here I'll assign the host address of 1 to the interface: (config-if)#ipv6 address aaaa:aaaa:aaaa:1::1/64 Let's take a look: R1#sho ipv6 interface fo/o FastEtherneto/o is up, line protocol is up IPv6 is enabled, link-local address isFE80::212:43FF:FEB9:2C70 Global unicast address (es): AAAA: AAAA: AAAA 1::1, subnet is AAAA:AAAA:AAAA:1::/64 [ANY] AAAA: AAAA: AAAA 1:212:43FF: FEB9 : 2C70, subnet is AAAA:AAAA:AAAA:1::/64 [EUI] [ --output truncated- ] Wait a minute-why is the EUI address still there? Because this isn't IPv4. You can have multiple addresses on an interface, and you do not need the secondary keyword to do SO. Be careful of this. If you want to remove the other address, you'll need to do it manually: R1 (config)#int fo/o R1 (config-if): #no ipv6 address AAAA:AAAA:AAAA:1::/64 eui-64 Now we've got our single IPv6 address that we've obsessively configured as :1: R1#sho ipv6 interface fo/o FastEtherneto/o is up, line protocol is up IPv6 is enabled, link-local address isFE80::212:43FF:FEB9:2C70 Global unicast address (es): AAAA: AAAA: AAAA 1::1, subnet is AAAA:AAAA:AAAA:1::/64 ANY] [--output truncated ] Remember how I've got R1 linked to R6? I configured R6's f0/0 interface with the ipv6 address autoconfig interface command. When I look at it, I see that something Chapter 37: IPv6 fascinating has happened. First, let's look at the interface configuration to show that I'm not nuts (like that's enough proof): interface FastEtherneto/o ip address 10.0.0.6 255.255.255.0 duplex auto speed auto ipv