v6 & DSL / Cable modems [was: Private use of non-RFC1918 IP space

Mark Andrews Mark_Andrews at isc.org
Thu Feb 5 03:45:38 UTC 2009

In message <20090205030522.13D152B21F3 at mx5.roble.com>, Roger Marquis writes:
> Mark Andrews wrote:
> > 	All IPv6 address assignments are leases.  Whether you get
> > 	the address from a RIR, LIR or ISP.  The lease may not be
> > 	renewed when it next falls due.  You may get assigned a
> > 	different set of addresses at that point.  You should plan
> > 	accordingly.
> Exactly the problem, and the reason A) IPv6 is not and will not be a viable
> option any time soon (soon being before the publication of an IPv6 NAT
> RFC), and B) why network providers (and other parties who stand to gain
> financially) are firmly against IPv6 NAT.
> >  If we could get a true accounting of the extra cost imposed
> >  by NAT's I would say it would be in the trillions of dollars.
> This is exactly the sort of hyperbole, like RFC4864's proposing that
> application-layer proxies are a viable substitute for NAT, that discredits
> IPv6 proponents.  Those who remember the financial industry's push for SET,
> a failed encryption technology, will be struck by the similarities in
> technical vs rhetorical arguments.
> Perhaps what we need is an IPv6 NAT FAQ?  I'm suspect many junior network
> engineers will be interested in the rational behind statements like:
>   * NAT disadvantage #1: it costs a lot of money to do NAT (compared to what
>   it saves consumers, ILECs, or ISPs?)

>   * NAT disadvantage #2 (re: your IPv6 address space) Owned by an ISP?  It
>   isn't much different than it is now.  (say again?)
>   * NAT disadvantage #3: RFC1918 was created because people were afraid of
>   running out of addresses. (in 1992?)
>   * NAT disadvantage #4: It requires more renumbering to join conflicting
>   RFC1918 subnets than would IPv6 to change ISPs. (got stats?)
>   * NAT disadvantage #5: it provides no real security. (even if it were true
>   this could not, logically, be a disadvantage)
> OTOH, the claimed advantages of NAT do seem to hold water somewhat better:
>   * NAT advantage #1: it protects consumers from vendor (network provider)
>   lock-in.

>   * NAT advantage #2: it protects consumers from add-on fees for addresses
>   space. (ISPs and ARIN, APNIC, ...)

	Only until the consumers get wind of any rip-off pricing.
	RIR's are charging ISP's about the same for a IPv6 /48 as
	they do the a IPv4 address.

>   * NAT advantage #3: it prevents upstreams from limiting consumers'
>   internal address space. (will anyone need more than a /48, to be asked in
>   2018)

	We already know some will need more than a /48.  /48 was
	only ever described as meeting the requirements of *most*
	business and consumers.
>   * NAT advantage #4: it requires new (and old) protocols to adhere to the
>   ISO seven layer model.

	Given were are running IP that is fiticious.
>   * NAT advantage #5: it does not require replacement security measures to
>   protect against netscans, portscans, broadcasts (particularly microsoft
>   netbios), and other malicious inbound traffic.

	What replacement?  You just buy a IPv6 router with a firewall.
	It will be about the same cost as a IPv4 router with a NAT.
> Roger Marquis
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark_Andrews at isc.org

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