kernel: nd6_setmtu0: new link MTU on ng29 (1218) is too small for IPv6

[Sami Halabi]

Hi,
I'm using a FreeBSD8.2-R-p5 in conjunction with MPD5.5 port for creating
pptp/l2tp tunnels.

I'm using MPPC (Compression & Encryption), my current onfiguration i use
only IPv4.

I keep getting in the logs the following:
Jan  3 19:15:21 mpd2 kernel: nd6_setmtu0: new link MTU on ng120 (1218) is
too small for IPv6
Jan  3 20:00:40 mpd2 kernel: nd6_setmtu0: new link MTU on ng151 (1218) is
too small for IPv6
Jan  3 20:09:27 mpd2 kernel: nd6_setmtu0: new link MTU on ng128 (1218) is
too small for IPv6
Jan  3 20:30:13 mpd2 kernel: nd6_setmtu0: new link MTU on ng128 (1218) is
too small for IPv6
Jan  3 20:34:33 mpd2 kernel: nd6_setmtu0: new link MTU on ng137 (1218) is
too small for IPv6
Jan  3 21:06:46 mpd2 kernel: nd6_setmtu0: new link MTU on ng105 (1218) is
too small for IPv6
Jan  3 21:42:48 mpd2 kernel: nd6_setmtu0: new link MTU on ng92 (1218) is
too small for IPv6
Jan  3 22:12:49 mpd2 kernel: nd6_setmtu0: new link MTU on ng137 (1218) is
too small for IPv6
Jan  3 23:21:50 mpd2 kernel: nd6_setmtu0: new link MTU on ng92 (1218) is
too small for IPv6
Jan  4 00:00:36 mpd2 kernel: nd6_setmtu0: new link MTU on ng105 (1218) is
too small for IPv6
Jan  4 00:34:48 mpd2 kernel: nd6_setmtu0: new link MTU on ng105 (1218) is
too small for IPv6
Jan  4 07:47:37 mpd2 kernel: nd6_setmtu0: new link MTU on ng100 (1218) is
too small for IPv6
Jan  4 08:31:55 mpd2 kernel: nd6_setmtu0: new link MTU on ng116 (1218) is
too small for IPv6
Jan  4 09:16:21 mpd2 kernel: nd6_setmtu0: new link MTU on ng123 (1218) is
too small for IPv6
Jan  4 12:55:32 mpd2 kernel: nd6_setmtu0: new link MTU on ng53 (1218) is
too small for IPv6

although the NG tunnels don't negotiate IPv6.

a close look to the MPD log i see that this happens for connections that
set MRU/MTU 1400.

I talked to MPD developer (Alexander Motin) and this isn't a MPD problem,
rather than a kernel issue as the logs say.

why this problem happens when no IPv6 is in work?

I don't want to disable ipv6 completely since i have plans in using it in
the near future.

Any help appreciated,
Thanks in advance,

-- 
Sami Halabi
Information Systems Engineer
NMS Projects Expert