ipv6 stateless autoconfig for global unique address

[paul amaral]

     Hi recently I started testing IPv6 internally using unique local address private space of FC00:abcd::/48. Everything has been working well accept I'm unable to get stateless autoconfig working for the unique global address with those ips, FC00:abcd::/48 to nodes on the network even though the windows 7 machines  are set to receive an unique global ipv6 address automatically. All machines on this network get the link-local address of FE80:: but not the FC00:abcd::/48 as a unique global. I'm assuming since they are getting the link local address that RA/DAD etc is working so im not sure why i can't get a unique global to be assigned to those machines with autoconfig. I'm assuming that for autoconfig to work with unique global i dont actually need to be using the unique global unicast range!!?

below is the configured interface on a cisco 6500 that the PC's connect to.

interface Vlan1

no ip redirects
no ip proxy-arp
ip route-cache same-interface
ip route-cache flow

ip ospf priority 10
ipv6 address FC00:ABCD:1::1/48
ipv6 enable
ipv6 dhcp server ipv6_stateless_pool
ipv6 ospf 2 area 0

thanks, paul

[cadet alain]

Hi Paul,

For RAs to be emitted you need to en able IPv6 routing with the ipv6 unicast-routing command and secondly if you want stateless autoconfig to work you must advertise a /64 and not a /48.

To verify if DAD/RA work as expected just issue debug ipv6 nd command.

Regards.

Alain.

[paul amaral]

cadet, thanks for the reply.

I have tested what you said and you are correct, i also looked around the internet and it mentions in wikipedia that "For SLAAC to work, subnets require at least a /64 address block" doesn't this mean that a /48 should work as well. I mean i tried a /48 and it obviously didnt' work going to the /4 as suggested did the trick. however is i really want to use a /48 on and interface does this mean im out of luck?

with the following config i was able to keep the /48 and enable SLAAC with a /64 however i dont know what problems this may cause.

int vlan1

ipv6 address FC00:ABCD:1::1/48
ipv6 enable
ipv6 nd prefix FC00:ABCD:1::/64

With the command "ipv6 nd prefix FC00:ABCD:1::/64" things work but will this cause any boundry connectivity issues?

[cadet alain]

With the command "ipv6 nd prefix FC00:ABCD:1::/64" things work but will this cause any boundry connectivity issues?

IMHO it shouldn't.

Regards.

Alain.