[v6ops] Re: Dynamic addresses

[Brian E Carpenter <[e-mail]>]

On 10-Aug-24 11:34, Daryll Swer wrote:
>  > But I don't understand the statement "breaks SLAAC on the LAN". A change of prefix renumbers the LAN, but that doesn't break SLAAC, it just causes SLAAC to renumber everything. It will only break active sessions.
> 
> It will break, on the host side, because they won't know to use the new prefix, until the pref/valid values expire.
> 
> https://www.6connect.com/blog/is-your-isp-constantly-changing-the-delegated-ipv6-prefix-on-your-cpe-router/ 

Thanks, yes, I knew that of course but the description of that as breaking SLAAC confused me. (When my ISP was changing prefixes after a CE power cut and reboot, the issue was masked by other effects of the power cut.)

> There's no reason to be promoting dynamic v6 prefixes, in addition to the SLAAC context, this makes it painful, for end-users to host anything at home, even basic SSH.

I completely agree.

    Brian

> 
> *--*
> Best Regards
> Daryll Swer
> Website: daryllswer.com <https://mailtrack.io/l/8b190af15371d42cba28cde7db9581f1c207dde9?url=https%3A%2F%2Fwww.daryllswer.com&u=2153471&signature=0564b87de4f69994>
> 
> 
> On Sat, 10 Aug 2024 at 04:56, Brian E Carpenter <[e-mail] <mailto:[e-mail]>> wrote:
> 
>     [Public service announcement: as of now, I'm spam-filtering messages with 'Digest' subject headers.]
> 
>     My ISP used to change my prefix whenever there was a power cut and the modem restarted. Now, it appears to be stable.
> 
>     But I don't understand the statement "breaks SLAAC on the LAN". A change of prefix renumbers the LAN, but that doesn't break SLAAC, it just causes SLAAC to renumber everything. It will only break active sessions.
> 
>     Regards
>          Brian
> 
>     On 10-Aug-24 10:13, Ted Lemon wrote:
>      > In order to do this, they would have to not renew a previously assigned prefix. I think some German telecoms used to do this as a privacy message, but it was operationally very difficult because it doubled demand for prefixes.
>      >
>      > Where are you seeing this irl, and how does it happen?
>      >
>      > Op vr 9 aug 2024 om 15:08 schreef Daryll Swer <contact=[e-mail] <mailto:[e-mail]> <mailto:[e-mail] <mailto:[e-mail]>>>
>      >
>      >     Tim, is there something we can do to encourage not only "more than a /64", but also encourage "static ia_pd to ensure the customer will not experience broken IPv6 connectivity due to ever changing prefixes".
>      >
>      >     Too many ISPs out there do dynamic IPs and breaks SLAAC on the LAN.
>      >
>      >     I feel this draft could be a powerful tool, in the hands of the end user to get these ISPs doing the right way of IPv6 more often.
>      >
>      >     --
>      >     Sent from my iPhone
>      >
>      >
>      >     On Fri, 9 Aug 2024 at 7:37 PM, Timothy Winters <[e-mail] <mailto:[e-mail]> <mailto:[e-mail] <mailto:[e-mail]>>> wrote:
>      >
>      >         Yes.  I've seen several instances of /64 being used for container networks on CPEs.
>      >
>      >         ~Tim
>      >
>      >         On Fri, Aug 9, 2024 at 9:38 AM The Multach's <[e-mail] <mailto:[e-mail]> <mailto:[e-mail] <mailto:[e-mail]>>> wrote:
>      >
>      >             So are these considered a LAN link prefix assignment under 7084 L2:
>      >
>      >             - Assignment of a /64 prefix for internal IPv6 communication between a
>      >             primary SoC and a secondary chip (e.g., a Wi-Fi chip which uses IPv6).
>      >
>      >             - Assignment of a /64 prefix for usage by an internal container or VM.
>      >
>      >
>      >             On 8/9/2024 7:56 AM, Timothy Winters wrote:
>      >              >
>      >              >
>      >              > On Thu, Aug 8, 2024 at 10:58 PM The Multach's <[e-mail] <mailto:[e-mail]> <mailto:[e-mail] <mailto:[e-mail]>>> wrote:
>      >              >
>      >              >     The following, while being user focused, fails to take into
>      >              >     account that
>      >              >     some of those prefixes may be used internally (or reserved for
>      >              >     internal
>      >              >     use) by the CPE or for ISP purposes and not assignable:
>      >              >
>      >              >     "SHOULD" (or an elongated exception for the above) would be more
>      >              >     appropriate.
>      >              >
>      >              >     LPD-4: After LAN link prefix assignment the IPv6 CE Router MUST
>      >              >     make the
>      >              >     remaining IPv6 prefixes available to other routers via Prefix
>      >              >     Delegation.
>      >              >
>      >              > I think this covers that case.   After local assignment, unused
>      >              > prefixes MUST be made available.
>      >              > LPD-2:  The IPv6 CE Router MUST assign a prefix from the delegated
>      >              >            prefix as specified by L-2 [RFC7084].
>      >              >
>      >              > 7084
>      >              >    L-2:   The IPv6 CE router MUST assign a separate /64 from its
>      >              >           delegated prefix(es) (and ULA prefix if configured to provide
>      >              >           ULA addressing) for each of its LAN interfaces.
>      >              >
>      >              >
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