Re: IPV4 to IPv6 migration

Brian,

On Jun 2, 2008, at 2:33 PM, Brian E Carpenter wrote:
>> On 6/1/08 9:36 PM, "Brian E Carpenter"  
>> <[email protected]> wrote:
>>>> You *NEVER EVER EVER EVER* NAT in IPv6.
>>> to say it quietly, there's never any reason to use nat in v6.
>>> the only valid reason in v4 is shortage of addresses,
>> No.  In addition to providing additional address space through the  
>> use of
>> non-uniqueness, people also use NAT to provide for provider  
>> independence.
>> Since IPv6 uses the same routing technology as IPv4 and it is  
>> essentially
>> just as hard to renumber a site in IPv6 as it is for IPv4, it  
>> follows that
>> this use of NAT will remain.
>
> No it doesn't, which is why the current discussions in the RRG matter.

I'm not clear what you're saying "no" about.  As you are fully aware,  
currently IPv6 does indeed use the same routing technology as IPv4,  
thus you have a choice:

a) get provider independent space and find somebody to route it
b) get provider aggregatable space and renumber if you change providers
c) use ULA and NAT into provider aggregatable space

Choose wisely.

Discussions in RRG _may_ matter, but as far as I can tell, they've  
made little progress particularly in the area of reaching any sort of  
consensus on pretty much anything.

> And please don't encourage IT departments to believe that adding and
> removing IPv6 prefixes is as hard as renumbering an IPv4 site.
> (Note, I didn't say it's easy, just that it isn't as hard.)

I'm merely repeating what folks in some large scale enterprise IT  
departments have told me regarding renumbering both IPv4 and IPv6.   
However, perhaps things have gotten better now that DHCPv6 servers are  
becoming available.

Summarizing what they've told me, in general you can make renumbering  
easy or hard regardless of whether you are using IPv4 or IPv6. Network  
management, firewalls, filters, and DNS configurations appear to be  
where the 'fun' lies. IPv6 makes things a bit harder and easier as it  
is much easier to mistype an address literal, but there are  
(generally) less places you have to type them.

In addition, in both IPv4 and IPv6, a renumbering event implies  
disrupted communications (particularly since the actual IP addresses  
are 'cached' in applications) and some folks care about that.

> It's about
> time we started looking at IPv6 as an opportunity to develop new and
> easier practices, rather than trying to force IPv6 into the IPv4  
> model.

Perhaps.  I suspect, however, most large network operators  
(particularly the commercial ones) will say "you first".

>> Of course, the alternative would be for everyone to use provider  
>> independent
>> address space, but we're all aware of the fact that this won't scale.
>
> Indeed. The PI model is very close to its sell-by date.

"We learn from history that we learn nothing from history." -- George  
Bernard Shaw

Regards,
-drc

_______________________________________________
global-v6 mailing list
[email protected]
http://mailman.apnic.net/mailman/listinfo/global-v6