Re: 2.4.21+ - IPv6 over IPv4 tunneling b0rked

Mika Liljeberg
2003-07-10T23:49:39Z

On Fri, 2003-07-11 at 02:39, CaT wrote:
> And having remembered /127 being mentioned as bad I changed the
> interface config to a netmask of /64. Dropped it and brought it
> up and it all works.
>
> There's something fundamental about ipv6 netmasks that I just don't
> understand...

Well, the thing is that prefix:: is a special anycast address that
identifies a router on the link prefix::/n, where n is the prefix
length. You had configured a 127-bit link prefix, meaning that you had
only one valid unicast address (last bit == 1) in addition to the router
anycast address (last bit == 0).

Normally, IPv6 networks are supposed to use 64-bit on-link prefixes but
the implementation can be written in such a way that other prefix
lengths can be configured.

Setting your tunnel prefix to /64 is certainly the right thing to do.

MikaL