Re: A common problem with SLAAC in "renumbering" scenarios

[Mark Smith <[e-mail]>]

On Wed, 13 Feb 2019 at 08:55, Lee Howard <[e-mail]> wrote:
>
> Seems like I may still disagree about the architecture of the Internet. . .
>
> On 2/12/19 9:53 AM, Ole Troan wrote:
> > Jan,
> >
> >> On 12 Feb 2019, at 04:36, Jan Zorz - Go6 <[e-mail]> wrote:
> >>
> >> Surprisingly, this is not causing major problems. Similar to IPv4, where changing the public IPv4 address on the CPE that is doing NAT to the internal LAN doesn't have considerable effect on the hosts inside (well, some sessions could drop on change, but that's the price you pay with NAT). In IPv6, if source and destination address is the same - if network in between changes and re-establishes quick enough - that should work (and it works in deployments out there ;) )
> > “Not considerable effect”?
> > It breaks all existing connections.
>
> This is packet switching, not circuit switching. Be resilient.
>

The questions are where and where best to implement that resilience?

IP layer? Within transport layer protocols? Within the transport
layer/application API? Within each application?












> > It requires updating DNS for services.
> Yes. We have dynamic DNS for that.
> > It might require updating static NAT entries and filtering rules.
>
> Static what entries? ;-)
>
> Filtering rules... you mean firewall rules? Yes, there should be a
> mechanism to update firewall rules when addresses change. PCP can do it.
> Or if we're in a Homenet context, the god box can glean it's PD and make
> that a variable in the firewall, or filter prefix first, and then
> evaluate host rules.
>
> > ...
> >
> > If we accept that IPv6 will work no better than IPv4 behind a NAT. I challenge you to give me one good reason to do IPv6 at all.
>
> IPv4 address prices continue to climb, and entry into the IPv4 Internet
> is cost prohibitive (anti-competitive) in many places. Even if you
> concede the need for translation to the legacy Internet, with IPv6 only
> the legacy fraction of traffic needs translation.
>
> With many layers of NAT4444... the odds of something changing midway in
> the topology climb pretty high, so the problems you cite are worse in
> IPv4 than in IPv6.
>
> Lee
>
>
> >
> > Ole
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