ULA prefix lifetime

[chriss]

Hi

I have the following scenario:

- a router with openwrt

- a (german) VDSL connection with IPv4 and IPv6

- a delegated IPv6 prefix (/56) that I use in my internal LAN segments

My problem:

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 
reboot/reconnect) and a new one. That's bad because the old one won't 
route anymore. simple solution: set the lifetime to sth like 5min or so 
and the old addresses gets deprecated fast enough.

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.

My idea would be to allow the user to set (optional) a ULA lifetime 
where one can specify the ULA prefix. The odhcpd process would then use 
this config entry and send RA with the respective lifetime.


I write to gather feedback and maybe alternative solutions and if a path 
/ PR for my solution would be accepted.



kind regards

//chriss