Deprecating IPv6 (Re: draft-bourbaki-6man-classless-ipv6-00)

[Mark Smith <[e-mail]>]

On 3 June 2017 at 00:56, Job Snijders <[e-mail]> wrote:
> Dear Lorenzo,
>
<snip>
>
>> Please stop trying to make IPv6 be the same as IPv4. That will take
>> away our ability to make the Internet better once IPv4 is gone.
>
> I believe there to be tangible merit in making IPv6 feel and look more
> like IPv4. Perhaps this becomes more apparent when one shifts the
> innovation focus from layer-3 to higher layers.
>
> Making IPv6 look more like IPv4 (for instance through broader adoption
> of DHCPv6 w/ routing options, and classlessness like in IPv4) will
> positively impact IPv6 deployment.
>

I think that's the fundamental agenda here, although perhaps not
realised. It is to devolve IPv6's capabilities and features to the
point where IPv6 isn't really much more than IPv4 with a different
packet format, and so the IPv4 operational practices people are
comfortable with can be directly applied to IPv6 without change. This
is because of the common human trait of intolerance of or resistance
to change.

If this proposal is accepted, then I think /120s will become the
defacto subnet size, despite what the draft says about /64s being the
recommended default. Here's the clue for why - RFC1918 addressed
networks I've seen, where IPv4 address space doesn't need to be
conserved (i.e., unlike public IPv4 address space), always use /24s as
the defacto subnet size. "Same-same" is easier for us humans than
"Same-different."

Why do I have a different perspective? My first networking protocol
was a more modern one than IPv4, Novell's IPX, derived from Xerox's
XNS. Learning and operating IPv4 networks after operating IPX networks
was a backwards step. The only major advantage that IPv4 provided over
protocols designed in the 1980s and 1990s, such as IPX, Appletalk and
CLNS, was that it provided organisations with Internet connectivity.
On many other criteria, IPv4 was far inferior - entirely
understandable, because it was fundamentally designed in the 1970s,
and then adapted over time to cope with being used to build a global
Internet work. It was never intended to be used to build a global
internetwork connecting billions of devices -

https://mailman.nanog.org/pipermail/nanog/2010-April/020488.html

IPv6 is actually the first true protocol designed to suit the global
"Internet" problem.

I have a few horrible stories of seeing IPv4 routers with 4 x /24s or
25 x /26s on the same interface because renumbering and changing
subnet masks of hosts into a single large enough subnet was more far
expensive than sub-optimal forwarding across the same link. An
impossible problem to have when the default subnet address space size
far exceeds the practical link-layer node attachment limits (and in
some cases impractical link-layer limits because of link layer
"excessive" addressing - does an Ethernet really need 48 bit MAC
addresses? Who's going to go close to attaching 2^46 nodes to one of
them? The ND cache resource exhaustion type of problem also exists at
layer 2 with switch tables ...)

I don't want to experience or see people experience those sorts of
IPv4 "right-sizing subnet" types of problems in IPv6.

Regards,
Mark.