On 2012-02-15 11:45, Martin Rex wrote:
> Brian E Carpenter wrote:
>> Martin,
>>
>>> One the one hand, the IETF was frowning upon NATs when they were
>>> developed outside of the IETF. But if you look at the IETFs
>>> (lack of) migration plan, the translation that you need in order
>>> to make old-IPv4 interoperate with new-IPv6, is actually worse than
>>> an IPv4 NAT.
>> I'm sorry, but *any* coexistence between RFC791-IPv4-only hosts and
>> hosts that are numbered out of an address space greater than 32 bits
>> requires some form of address sharing, address mapping, and translation.
>> It doesn't matter what choice we made back in 1994. Once you get to the
>> point where you've run out of 32 bit addresses and not every node can
>> support >32 bit addresses, you have the problem.
>
> But what is your point?
>
> With a fully backwards compatible transparent addressing scheme,
> a much larger fraction of the nodes would have switched to actively
> use IPv6 many years ago.
Why? They would have needed updated stacks. The routers would
have need updated stacks. The servers would have needed updated
stacks. The firewalls would have needed updated stacks. The load
balancers would have needed updated stacks. Many MIBs would have
needed to be updated. DHCP servers would have needed to be updated.
ARP would have needed to be updated, and every routing protocol.
Why would the economic incentives have been significantly different?
> You would not have two distinct routing tables for two independent
> Internets, but a single routing table for a single Internet.
True, but why is this a particular advantage? It wouldn't have
affected the need for an update to BGP4, for example.
>
> And the first network interfaces that would be using >32-bit
> IP-addresses exclusively would have been networking equipment of
> ISPs that does not need to be IPv4-addressable by everyone and his dog
> anyway (that is not so much different from the /10 shared address space
> that CGNs will be using).
Neither is it so much different from dual stack routing, which has been
working for, what, 15 years now? I don't see the comparison with CGN
though, which is a carefully engineered single bottleneck of failure,
in contrast to dynamic routing.
> The necessary changes to applications would be minimal,
> the "happy eyeballs" contortion completely unnecessary
As someone else said, this is to do with multihoming
and multi-interfacing; the fact that there are two address
lengths is a side-issue. We would still have needed to update
the socket interface to deal with >32 bit addresses, and ditto
the DNS.
> and the security assessment for an IPv6 enabled network
> *MUCH* simpler.
I agree that the fact that IPv6 has a different feature list
from IPv4 has provided entertainment for security analysts.
I will shut up on this topic and get back to IPv6 deployment.
Brian
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