Date: Sun, 12 May 2013 13:30:02 -0700 From: Kevin Oberman <rkoberman@gmail.com> To: sthaug@nethelp.no Cc: jason@b0rken.org, jinmei@isc.org, freebsd-net@freebsd.org Subject: Re: IPv6 tunnel MTU of 1480 not effective Message-ID: <CAN6yY1uJjxNSbdbhKcaLanbjrGr_1e7E6_3cXB-OjQg9R7Zr%2Bw@mail.gmail.com> In-Reply-To: <20130512.130304.74693108.sthaug@nethelp.no> References: <20130509.110631.74720486.sthaug@nethelp.no> <CAN6yY1seGF8AP0%2BstgUaMUFBxvM9eAx5s1WgBLcpxE21pTFtTg@mail.gmail.com> <m2a9o063ds.wl%jinmei@isc.org> <20130512.130304.74693108.sthaug@nethelp.no>
next in thread | previous in thread | raw e-mail | index | archive | help
On Sun, May 12, 2013 at 4:03 AM, <sthaug@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@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@gmail.com
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?CAN6yY1uJjxNSbdbhKcaLanbjrGr_1e7E6_3cXB-OjQg9R7Zr%2Bw>