Only 5x IPv4 /8 remaining at IANA

Thu Oct 21 23:55:14 UTC 2010

As long as there are IPv4 clients, you need IPv4 servers to serve them.
Software written (well) for IPv6 can serve both IPv4 and IPv6 from the
same socket, so long as you set the socket option IPV6_V6ONLY
correctly (default except for errant BSD code), but, the machine
needs to have a working IPv4 address to do this.

In its natural state, IPv4 and IPv6 cannot talk to each other. They are
separate protocols just as IP and IPX and Appletalk are separate.
(ignoring the IPX/Appletalk over IP things for the time being).

There are some ways to build some translation facilities, but, it's
not trivial and there are no translation facilities that work even in all
the same cases that NAT44 currently works.

If you want to talk to both IPv4 and IPv6, you'll need dual stack. Thus,
we should dual-stack as much of the existing infrastructure before IPv4
runout as possible and dual stack the rest as quickly as possible
thereafter. After runout, all new stuff will be effectively IPv6 only, or,
IPv6 with very degraded IPv4 capabilities.

If you're stuff needs reachability with those new IPv6 only members
of the internet (both clients and servers, although clients will
dominate the numbers initially), then, you really need dual stack.

Owen

On Oct 21, 2010, at 8:07 AM, Ben Butler wrote:

> Hi,
> 
> Showing my ignorance here, but this is one of the things I have wondered, given that we run both v4 and v6 for a period of time on the Internet, presumably at one time or another a particular resource may only be able in v4 land, then v4 and v6, then finally v6 only.
> 
> I have never been particularly clear how an end network that exists only in v4 or v6 address space is able to access a resource that only exists in the other.  Is can sort of see some freaking huge NAT box type thing that summarizes v6 in a v4 address scope or contains the v4 address range at some point inside the v6 address space - but how can a v4 host get to a hot in v6 world that sits outside this without going through some form of proxy / nat gateway between the two.
> 
> Or are the two simply not inter-communicable?
> 
> Ben
> 
> -----Original Message-----
> From: Patrick Giagnocavo [mailto:patrick at zill.net] 
> Sent: 21 October 2010 15:59
> To: Owen DeLong; NANOG
> Subject: Re: Only 5x IPv4 /8 remaining at IANA
> 
> On 10/21/2010 4:28 AM, Owen DeLong wrote:
> 
>>> Actually for those of my clients in one location, it served as an
>>> impetus to extend a contract with Level3 for another 3 years - with
>>> their existing allocation of a /24 of IPv4 addresses included.
>> 
>> All well and good until some of their customers are on IPv6...
>> Then what?
> 
> I'm sorry, can you expand on exactly what you mean by this?
> 
> Are IPv6 connected machines unable to access IPv4 addresses?
> 
> Or is this more IPV6 fanboi-ism?
> 
> --Patrick
> 
> 
> 
> 
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