IPv6 tunnel MTU of 1480 not effective

[Kevin Oberman]

On Sun, May 12, 2013 at 4:03 AM, <sthaug at nethelp.no> wrote:

> > > > > However I'm only able to send IPv6 packets from my host that fit
> an MTU
> > > > > of 1280 even though I've set the tunnel interface and per-route
> MTU to
> > > > > 1480, based on the "outer" ethernet connection having an MTU of
> 1500.
> > > > > Hurricane Electric supports this and I've set the MTU to 1480 on
> their
> > > > > side as well.
> > [...]
> > > I complained about this at least a couple of years ago and was told by
> the
> > > developer (I don't recall exactly who any more) that it was right and
> would
> > > not be changed. I really would love to see this reconsidered before
> IPv6
> > > becomes much more popular as it will simply cause confusion, but I,
> too,
> > > fear that it is a lost cause.
> >
> > What's "this" (to reconsider)?  That ping6 fragments outgoing packets
> > at 1280 octets (by default)?  Or, more in general whether any outgoing
> > IPv6 packet can initially honor the interface MTU?
>
> What I want to happen is: When I use ping6 *and explicitly specify a
> packet size using the -s option*, I want the interface MTU to be
> honored. I don't want to have to specify -m as a sort of extra "yes,
> I really really mean it".
>
> This is, in my opinion, by far the least surprising behavior for the
> user - and would then work the same as the IPv4 ping command.
>
> It looks like an extremely simple change to make in the ping6.c file.
>
> (Long term, I would like ping and ping6 to become *one* program with
> default IPv4 or IPv6 based on the destination specified, and options
> -4 / -6 like telnet has. Same for traceroute / traceroute6. However,
> this is an aside.)
>
> Steinar Haug, Nethelp consulting, sthaug at nethelp.no
>

Sorry to be so hackneyed, but...
+1

Sorry that I was unclear (and may have been last time, too).

-- 
R. Kevin Oberman, Network Engineer
E-mail: rkoberman at gmail.com