[AusNOG] Prediction: Google et. al. may artificially penalise IPv4 clients

[Geoff Huston]

> On 2 May 2017, at 4:30 pm, Mark Newton <newton at atdot.dotat.org> wrote:
> 
> Allow me put a few word into Geoff’s mouth to summarize his comment:
> “IPv6 in operation is no worse than IPv4.”


If IPv6 had an entirely different fragmentation behaviour and if deployed equipment did not discard IPv6 packets with extension headers and all we were talking about was in effect the relative differences in various forms of boot configs then maybe you could be right Mark.

But those are two significant problems right there that go right to the heart of this protocol.

If you want to avoid packet mangling out there you need to ensure that every IPv6 packet you send is no larger than 1280 octets and you need to avoid fragmentation completely. And everybody else needs to do the same.

Today, many of the  problems that occur in V6 are masked by dual stack - if it fails in 6 there is always 4. And the implications of this observation is that we just don’t care about broken equipment that discards packets with Extension Headers or firewalls that block ICMPv6 PTB, or systems that ignore incoming PTB messages. Because there is always 4 to make it work. But it seems to me that a protocol that is incapable of reliably supporting any packet over 1280 octets in size is a broken protocol. And all the protestations that claim this is just a minor side issue or that vendors will lift their game just can’t fix that. 

So how are you going to make it better Mark?

:-)