IPv6 design, deployment, standards, and best practices.
Captainserious
New Member
Posts:
25
Joined:
Wed Oct 12, 2011 6:04 am
Certs:
CCNA

IPv6 Stateless Autoconfiguration issues.

Tue Jan 24, 2012 4:17 pm

Hi guys.

I'm currently implementing IPv6 over an Anycast network for a University project. I've just managed to get Anycast working which is a huge milestone, but I'm experiencing issues.

I have (erroneously or otherwise) configured router-to-router links with the command "ipv6 address autoconfiguration", so that each interface will be assigned an IP address automatically. Now that I've come to ping from one side of the network to the other, I can't. I have a sneaky feeling that I can't use autoconfiguration in this way. Am I right?

Note - I have enabled OSPFv3 over the whole network and it is working fine (adjacancies and all), which initially led me to believe that I could use autoconfig. as I am doing. I looked in the routing table, and all of the routers have the autoconfig. prefix (FE80::/10) going to "Null0" interface. This would explain why the pings aren't working, but basically I am unsure as to whether I have to manually address all the routers' interfaces or not.

Cheers.

CS.

User avatar
srg
Post Whore
Posts:
1723
Joined:
Thu Dec 30, 2010 2:05 pm
Certs:
CCIE SP, CCNP SP, CCNP, CCDA, CCNA DC/W, HP MASE

Re: IPv6 Stateless Autoconfiguration issues.

Tue Jan 24, 2012 4:32 pm

FE80 is link-local addresses and cannot be routed, thats why you see it nullrouted. On router-router links you should statically assign IP adresses, and you can use SLAAC on the end-users/clients.

verbose: the ipv6 address autoconfiguration implies that you have a router on the other end of the link with a public prefix that announces this via RA, and the interface with autoconfiguration will derive a valid IPv6 address from that prefix. The link-local FE80 address is derived as soon as you activate IPv6 on your interface with ipv6 enable.
som om sinnet hade svartnat för evigt.

Captainserious
New Member
Posts:
25
Joined:
Wed Oct 12, 2011 6:04 am
Certs:
CCNA

Re: IPv6 Stateless Autoconfiguration issues.

Tue Jan 24, 2012 4:57 pm

Ok thanks.

So the reason it's possible is that any device that doesn't have a link-local address can be routed because it's source address doesn't change as it's being routed (only the MAC)?

I was pinging from a router, so I guess that router had a non-routable address and that was why it was being dropped. I've just tried pinging a non-router from a non-router across the network and it worked, so I assume that was the issue then.

Thanks for your help, I'm still trying to get my head round IPv6!

User avatar
srg
Post Whore
Posts:
1723
Joined:
Thu Dec 30, 2010 2:05 pm
Certs:
CCIE SP, CCNP SP, CCNP, CCDA, CCNA DC/W, HP MASE

Re: IPv6 Stateless Autoconfiguration issues.

Wed Jan 25, 2012 3:39 am

Captainserious wrote:So the reason it's possible is that any device that doesn't have a link-local address can be routed because it's source address doesn't change as it's being routed (only the MAC)?
Uh yeah.. sortof ;). Every device does have a link-local address since this is mandatory for IPv6 and you get this as soon as you activate IPv6 on an interface. The public address is 'optional', but needed if you want to communicate outside of your interfaces segments.
som om sinnet hade svartnat för evigt.

'

Return to IPv6

Who is online

Users browsing this forum: No registered users and 8 guests