[radvd-devel-l] Wildcard Interface Addresses

[Pekka Savola]

On Mon, 11 Feb 2008, Norman Rasmussen wrote:

> Woops, forgot the context:
>
> I'm trying to enabled IPv6 for my VPN server, so ppp0 is my existing
> internet connection, and ppp<other> are my vpn clients.  I want to assign
> each client their own IPv6 address - /128 only as these are roaming laptops
> so they don't have a network behind them anyways.

Are you sure?  Your client could be a laptop which has a PDA or mobile 
phone behind it, as well.

> pppd is setting up the fe80::prefi, but not my global prefix.  I did a quick
> test, and even if I do announce the prefix down the ppp link, my vista
> clients are not using it.  Any ideas?

Which prefix did you try to advertise?   The RFCs and implementations 
require that you advertise a /64, otherwise it's ignored from the 
address configuration perspective.  If you advertised a /64, I don't 
know why Vista would have ignored it.  If you advertised something 
else, that's the reason.

Even if you go along with /128's, how do you get those configured 
on your laptop clients?   Radvd can't do that due to prefix length 
restriction mentioned above.  How will the clients talk to other 
clients using ithe same prefix?

It seems that what you intend to do is not compatible with IPv6 
addressing mechanisms.  My suggestion is that you advertise a 
different /64 on each link (for which you don't need the interface 
address feature) or you use a different mechanism for assigning 
addresses on the clients (for example, IKEv2 supports IPv6 address 
configuration payloads) where you don't need to assign or advertise a 
global IPv6 prefix on the links in the first place.

-- 
Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings