I finally figured out how to get IPv6 on my outside and inside interfaces of my router (Cisco 2821) and on the uplink port on my switch (Cisco 3750). All three IPv6 addresses are pingable from the outside world. The switch and router are connected with OSPF. I am not able to add the eui-64 prefix to my VLAN. What do I need to do to add IPv6 to my VLANs?
interface GigabitEthernet0/0 description OUTSIDE ip address dhcp ip nat outside ip virtual-reassembly in duplex auto speed auto ipv6 address dhcp ipv6 address autoconfig ipv6 enable ipv6 nd dad attempts 0 ipv6 nd autoconfig default-route ipv6 dhcp client pd hint ::/64 ipv6 dhcp client pd COX ! interface GigabitEthernet0/1 description INSIDE ip address 10.0.0.9 255.255.255.252 ip nat inside ip virtual-reassembly in ip ospf authentication message-digest ip ospf message-digest-key 1 md5 7 0702364F1F514A51 ip ospf 10 area 0 duplex auto speed auto ipv6 address 2600:8807:8500:419::/64 eui-64 ipv6 address autoconfig ipv6 enable ipv6 nd autoconfig default-route ipv6 ospf 10 area 0
interface GigabitEthernet1/0/4 description LINK TO MIKEROUTER no switchport ip address 10.0.0.10 255.255.255.252 ip ospf authentication message-digest ip ospf message-digest-key 1 md5 7 10431E1A544F415F ip ospf 10 area 0 ipv6 address autoconfig ipv6 ospf 10 area 0
interface Vlan10 description MIKERO ip address 10.10.17.1 255.255.255.0 ip ospf 10 area 0 ipv6 address autoconfig default ipv6 enable ipv6 ospf 10 area 0
GigabitEthernet0/0 is in client mode Prefix State is SOLICIT (1) Information refresh timer expires in 23:59:34 Address State is OPEN Renew for address will be sent in 11:59:34 List of known servers: Reachable via address: FE80::A64C:11FF:FE8A:DADA DUID: 000100015567324DF8BC123EDDA4 Preference: 0 Configuration parameters: IA PD: IA ID 0x00030001, T1 43200, T2 69120 Prefix: 2600:8807:8502:ED00::/56 preferred lifetime 86400, valid lifetime 86400, expired IA NA: IA ID 0x00030001, T1 43200, T2 69120 Address: 2600:8807:9F02:1:B943:EACC:9C61:BC25/128 preferred lifetime 86400, valid lifetime 86400 expires at Mar 07 2018 10:37 AM (86375 seconds) DNS server: 2001:578:3F::30 DNS server: 2001:578:3F:1::30 Information refresh time: 0 Prefix name: COX Prefix Rapid-Commit: disabled Address Rapid-Commit: enabled Prefixes sent as hint: ::/56
So now you want to be running firmware new enough that it copes well with DHCPv6 prefix delegation. Upstream (cox.net?) will be sending you ICMPv6 router advertisements (RA), which will probably have the "managed configuration" flag on, meaning you should do DHCPv6 to find out more. The router will be using its link-local scope address as sender for the RA, starting fe80::/64; that's your v6 gateway address. Basically all IPv6 subnets are /64 at the vlan, so with a /56, you have 8 bits to do subnetting with. The DHCP prefix delegation will tell you which one is used on the outside interface, perhaps the one with 00 as the subnet. The rest you can use on inside subnets, be they LAN, WIFI, guest WIFI, DMZ or whatever.
-- Jim Leinweber