[arin-ppml] ARIN-prop-127: Shared Transition Space for IPv4 Address Extension

Jack Bates jbates at brightok.net
Fri Jan 21 09:32:08 EST 2011

On 1/21/2011 4:17 AM, Owen DeLong wrote:
> This has a lot more to do with content not being accessible on IPv6 and
> not having a solution for IPv4-only customer devices to reach IPv6
> content than it does with the access networks not deploying IPv6.

I suspect content will hard switch to v6 faster than home routers will.

> The access providers generally agree that native IPv6 or 6rd can be deployed
> easier and quicker than NAT444 for the problems that can solve.

We can provide, doesn't mean customers will switch their home gear.

> The difficult comes when they deal with users, even users that have IPv6
> access, that need to reach IPv4 content for whatever reason. This is where
> NAT444 is pretty much the only viable alternative currently on the table.

Agreed. There will still be some v4 content, even if most will switch to 
v6 as soon as it's viable QOS wise for them to do so.

> I will note that even the people asking for this /10 are saying that they
> really don't want to use it, but, they don't see any alternative.

Reuse their existing space. A single /18 of all my address space would 
be fine for me to handle NAT444, and not a big deal to duplicate it 
around the different network areas. I suspect I'll actually go with 
something smaller, and probably from the DHCP pools which don't utilize 
static addressing (perhaps that /20 in use by the cell phones).

>> The proposal doesn't mention another source of unique IPv4 addresses
>> that could be used for this purpose - the ISPs' existing assignments.
> That's really a non-starter.

Why? We have address space already. Why not duplicate it around the 
network? What does some arbitrary /10 give me that my existing space 

> On the other hand, what I think you will see if this policy does get bogged
> down is a situation where many of the larger providers that are asking
> for this will each go apply for their own allocations and they may or may
> not coordinate sharing that with others. I think that is a far less desirable
> alternative than getting this policy through.

They will apply for allocations anyways. They will ask for address space 
for as long as they possibly can. The fact is, most of the networks who 
need NAT444 run vast amounts of dynamic space, and we can easily reuse 
that space for NAT444.

> I find myself having to agree with Bill here. I'm not 100% convinced this is
> the right thing to do, and, I was pretty opposed to it from the understanding
> I had of the issue when it was presented to IETF. However, at this time, I'm
> leaning more towards the belief that this is one of the three things in the
> IPv4 end game that we really need to just hold our noses and do.

I think ARIN should push for education of NAT444 address reuse with 
existing address space. Once an ISP does decide to shift to NAT444, 
they will quit hitting up the freepool for more space. I expect the 
major shift of NAT444 as soon as v6 is the mainstream protocol, reducing 
the load and problems associated with NAT.


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