Re: [v6ops] AWS ipv6-only features

[Nick Buraglio <[e-mail]>]

Thank you for writing some information on ULA, it's an important part of
IPv6 and not really discussed enough. Perhaps we should start another
thread, but I'd like to hear more about when you see this behavior:

*"ULAs are preferred over GUAs, so when a host is presented with both a ULA
and GUA as possible ways to reach a destination, the host will select the
ULA. Once the ULA destination address is chosen, the host will then choose
its ULA as a source address to reach the ULA destination. This preference
of ULA addressing over GUA addressing is the mechanism that provides
internal network connectivity independence from concurrent external
Internet connectivity."*

In testing and in practice I have experienced that exactly the opposite of
this is true in both day-to-day use and every single explicit test I have
done where ULA and GUA are present on both sides with a variety of hardware
platforms and operating systems. GUA is used in every scenario I test when
the AAAA records are all matching (i.e. appropriately correct DNS). I'm
happy to learn that I am incorrect, as it would make certain things easier,
but nothing so far in my experience has shown the described behavior.
Seemingly relevant to the discussion at hand, and definitely relevant to
enterprises and providers actively using or considering ULA.

nb

On Thu, Nov 25, 2021 at 2:49 PM Mark Smith <[e-mail]> wrote:

>
>
> On Fri, 26 Nov 2021, 07:41 Clark Gaylord, <[e-mail]> wrote:
>
>> Yeah AWS hold their cards close and don't seem to engage the community,
>> but they do have decent IPv6 coverage across the services. Notwithstanding
>> that the whole VPC concept has the whiff of ancient days about it; tonight
>> we're gonna network like it's 1999!
>>
>> EC2 as part of the address is a great idea. I am so stealing that (can't
>> believe I haven't thought of it.)
>>
>
> It's a terrible idea. The "Unique" in ULA is on purpose.
>
> Getting IPv6 private addressing right
> https://blog.apnic.net/2020/05/20/getting-ipv6-private-addressing-right/
>
>
>>
>> On Thu, Nov 25, 2021, 15:09 Mark Smith <[e-mail]> wrote:
>>
>>>
>>>
>>> On Thu, 25 Nov 2021, 23:51 Ca By, <[e-mail]> wrote:
>>>
>>>> Fyi, aws has gone beyond perfunctory ipv6 support and has released a
>>>> series of enhancements, with a focus on ipv6-only scenarios, including
>>>> nat64 / dns64
>>>>
>>>>
>>>> https://aws.amazon.com/about-aws/whats-new/2021/11/aws-nat64-dns64-communication-ipv6-ipv4-services/
>>>>
>>>> AWS has lapped Google and Azure in advanced network features, which is
>>>> really surprising given the early muscle Google developed at IPv6 launch
>>>> and a stronger need to differentiate …
>>>>
>>>
>>> AWS failed to do ULAs properly. 'ec2' could be a random global ID, but
>>> unlikely when their service is "EC2".
>>>
>>> Matters more here because they're exposing that to all of their tenants.
>>> I think GUAs would have been better for these internal all tenant services.
>>>
>>> I've never seen AWS participate here in 20 years, unlike G and M.
>>>
>>>
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