Re: [v6ops] draft-palet-v6ops-464xlat-opt-cdn-caches **Call for Adoption**

While I'm very supportive of 464xlat as a transition technology, and while
I was very optimistic about this approach
at first (and may even have suggested some of the proposals included in the
draft), on subsequent
reflections I continue to have significant concerns about the fragility of
this approach.
Implementing this in a way that works well with a generic CDN  (ie, one not
managed
by the operator) will require a significant amount of state and complexity
in CPE devices.
It only will take one or two bad CPE implementations to result in CDNs
being forced to switch
content to IPv4-only to address user complaints, which would undo what this
is trying to achieve.

In particular, the fundamental issue is that the RR sets returned for A and
AAAA records
from many CDNs are not 1:1 and also change frequently during the lifetime
of connections.

As such, I continue to have serious reservations about trying to move this
forwards
as anything other than Experimental.  If we do move forward, the DNS-based
approach
needs to be comfortable moving lots more state into the CPE than I recall
seeing
in the last version of this that I read.   In particular, if DNS sees
changes to {A,AAAA}
pairings, it is critical to only apply those to future connections and not
break existing
connections, meaning that CPEs need to keep these rewrite rules associated
with stateful connection tracking.

With the use-case for this being IPv4-only devices, a question may be
whether
it is better to focus on trying to get those devices to implement native
IPv6 support
while handling them via a CLAT in the CPE for the time-being.  Alternately,
lw4o6
addresses the "offload stateful NAT off of the CPE" in a much less fragile
way.

        Erik

On Wed, Dec 11, 2019 at 2:25 PM Ron Bonica <rbonica=
40juniper.net@dmarc.ietf.org> wrote:

> Folks,
>
>
>
> Each week between now and IETF 107, we will review and discuss one draft
> with an eye towards progressing it.
>
>
>
> This week, please review and comment on
> draft-palet-v6ops-464xlat-opt-cdn-caches.
>
>
>
> When reviewing this draft, please indicate whether you think that V6OPS
> should adopt it a s a work item.
>
>
>
>                                                       Fred and Ron
>
>
>
> Juniper Business Use Only
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