ULA prefix lifetime

[Sebastian Moeller]

Hi Michael,


> On 20. Nov 2024, at 19:33, Michael Richardson <mcr at sandelman.ca> wrote:
> 
> 
> chriss <chriss-lists at posteo.mx> wrote:
>> I happens that I have to reconnect my VDSL (update of router, tripped over
>> cable, whatever) - with that I get a new IPv6 prefix delegated. Now my
>> clients have 2 prefixes/addresses. The old one (before the router
> 
> :-(
> {Your ISP should avoid that kind of thing; IPv6 being plentiful there is no
> reason not to just statically allocate them all into the (radius) database,
> and just renumber people when there are major re-balancing.}

[SM] Some users actually desire an easy way to gain a new prefix, to make tracking/being receiver of a DOS slightly harder. Like it or not, that is a use case end customers demand and ISPs deliver... (ISPs also use this to differentiate business type contracts that contain stable prefixes...)

> 
>> Now my ULA addresses have also a lifetime of 5min - which is bad because
>> after 5 min of router downtime (update) I lose my local delivery between
>> clients.
> 
>> My solution (to this very specific and edge case problem) would be to set a
>> large lifetime for ULA prefixes and use a short one for WAN delegated.
> 
> That sounds like a good idea
> I'd also say that netifd/dnsmasq ought to automatically deprecate GUAs that
> go away when they are not renewed after a network outage.

[SM] I might be confused, but the issue is, OpenWrt not saving state persistently the router has no idea which prefixes and GUAs are in use...  I guess (and I mean that this is pure speculation) the router could trap on GUAs it has no upstream path for and serve a deprecation request to the GUA (not even sure that is possible).

> 
> 
> --
> Michael Richardson <mcr+IETF at sandelman.ca>   . o O ( IPv6 IøT consulting )
>           Sandelman Software Works Inc, Ottawa and Worldwide
> 
> 
> 
> 
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