On Thu, May 9, 2013 at 2:06 AM, <sth...@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. > > > > This issue is evident when I try to send IPv6 pings larger than 1280 > > bytes to the remote tunnel peer. The outgoing echo request is chopped > > into two fragments, while the response comes back in one fragment, as > > follows: > > > > % ping6 -c 1 -s 1432 2001:470:1f08:84f::1 > > PING6(1480=40+8+1432 bytes) 2001:470:1f09:84f::2 --> 2001:470:1f08:84f::1 > > 1440 bytes from 2001:470:1f08:84f::1, icmp_seq=0 hlim=64 time=1.514 ms > > This is a "feature" (i.e. it's documented). See the ping6 -m option: > > -m By default, ping6 asks the kernel to fragment packets to fit into > the minimum IPv6 MTU. The -m option will suppress the behavior > in the following two levels: when the option is specified once, > the behavior will be disabled for unicast packets. When the > option is more than once, it will be disabled for both unicast > and multicast packets. > > In my opinion this behavior badly breaks POLA, and should be removed > (i.e. the current -m behavior should be the default). > > I have no great hope in getting this changed, though... > > Steinar Haug, Nethelp consulting, sth...@nethelp.no > _ > Thanks, Steiner.
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. Please prove me wrong! -- R. Kevin Oberman, Network Engineer E-mail: rkober...@gmail.com _______________________________________________ freebsd-net@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "freebsd-net-unsubscr...@freebsd.org"
