v6 & DSL / Cable modems

Paul Vixie vixie at isc.org
Fri Feb 6 01:20:01 CST 2009


"Ricky Beam" <jfbeam at gmail.com> writes:

> ... In the mid-80's, /8's were handed out like candy because there were
> "lots of address space" and "we'll never use it all." ...

ahem.  allow me to introduce myself.  i was alive and actively using the
internet in the mid-80's, and when we got our /8 it was justified very
differently than what you said.  we had field offices in 100 countries and
we had 130,000 employees and our internal network spanned five continents.
(we thought long and hard about netmasks before we started rolling it out.)

it was not true in Digital Equipment Corporation's (DEC's) case that a /8
was "handed out like candy" or that the justification was anything like
"lots of address space" or "we'll never use it all".

> IPv6 was designed to "not need DHCP."  DHCPv6 has come about since people
> need more than just an address from "autoconfiguration".

IPv6 promised a lot of things, like no-forklift insertion of IPv6 into the
existing IPv4 network, and "some hosts, such as printers, might need never
be upgraded".  a lot of those promises were trash, just stuff that folks had
to say to get through whatever they were getting through.  as much as i'd
like a time machine to go back and whisper "yo, dude, that's *so* not gonna
happen" in some ears, what matters to us now is not what IPv6 was promised
to be or even what it could have been but instead: what it could now become.

> I can recall many posts over the years from the IPng WG telling people
> they didn't need DHCP.

some people drink their own cool-aid.  advice: get better at ignoring them.

i dislike the compromises and mistakes other people will make when faced
with NAT, and i don't want to live in a world dominated by products and
services containing those compromises or those mistakes.  i want end-to-end
so i can stop budgeting half a day for each VoIP phone i send home with an
employee.  i don't want to remap addresses mid-path because i just know that
the best programmers are the lazy ones and they WILL encode endpoint IP addrs
in their sessions no matter what we tell them or how much it hurts us all.

IPv6 coulda been and shoulda been lots of better things than we're getting,
but due to circumstances beyond our present control, it's what we've got to
work with, and it could still avoid a lot of problems whose alternative
costs could be higher (NAT, double NAT, triple NAT, IPv4 markets, IPv4
black markets, IPv4 route piracy, explosive deaggregation, to name some).

the most fundamental re-think required to wrap a brain around IPv6 compared
to IPv4 is that we will never run out of addresses again unless someone
(ignorantly) assigns a /125 to a LAN and needs more than 7 hosts thereon,
or something similar.  that part of IPv4's dark past will not follow us to
IPv6 and we can stop thinking all related or derivative thoughts, for IPv6.
but, and this matters so please pay attention, IPv6 does nothing to solve
the routing table problem that IPv4 has had since 1995 or so, and IPv6 can
amplify this part of IPv4's dark past and make it much worse since there can
be so many more attached devices.

the fundamental implication is, forget about address space, it's paperwork
now, it's off the table as a negotiating item or any kind of constraint.
but the size of the routing table is still a bogeyman, and IPv6 arms that
bogeyman with nukes.
-- 
Paul Vixie




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