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

[Jan Zorz - Go6 <[e-mail]>]

On 12/02/2019 15:53, 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. It
> requires updating DNS for services. It might require updating static
> NAT entries and filtering 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.

Not entirely true. If the address on WAN link changes and PD stays the 
same - then nothing changes on the host itself, but it's just a change 
in network topology "in the middle". In IPv6 you are not using your WAN 
address of CPE in DNS for services, do you? I usually put in DNS 
addresses of hosts behind CPE :)

Consider this (as end-user) as topology change that can occur in every 
part of the network and does not affect your network behind the CPE.

Cheers, Jan