I'm not an expert at ipv6, but just a guess:

Dustin Sallings <dustin@spy.net> wrote:
>
>	I'm having a strange problem with an IPv6 router/firewall.  I've
>got three interfaces:
>
>juan# ifconfig de0
>        inet6 3ffe:b80:d9:1::1 prefixlen 48

This is 3ffe:0b80:00d9:0001:....
                      ^- here is prefixlen 48

>juan# ifconfig ex0
>        inet6 3ffe:b80:d9::1 prefixlen 48

This is 3ffe:0b80:00d9:0000:....
                      ^- here is prefixlen 48

>Aug 18 23:44:48 juan /netbsd: nd6_lookup: failed to add route for a
>neighbor(3ffe:0b80:00d9:0001::0001), errno=17

Both de0 and ex0 have the same network prefix (3ffe:0b80:00d9) at
prefixlen 48.

>	This also prevents machines on the wireless LAN from talking.  17
>is EEXIST for those who don't want to look it up, however I can't find any
>references that would match:

>juan# netstat -rn | egrep 3ffe:b80:d9
>3ffe:b80:d9::/48              link#1                    UC          0
>0   1500  ex0

That's the one, right there.  You've tried to put both interfaces on
the same network.  Try a prefixlen of 64 if you want the two to be
different networks.

jdarrow

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