[CentOS] IPv6 token with /60 and prefix delegation

Mon May 9 20:26:17 UTC 2022
Chris Adams <linux at cmadams.net>

Once upon a time, Kenneth Porter <shiva at sewingwitch.com> said:
> Right now it's a CentOS 8 system running NetworkManager. The LAN
> side is going to run the Kea DHCP server but for now I'm just trying
> to get the WAN side going.

The typical IPv6 CPU router setup is:

- WAN receives Router Advertisement that says there is stateful config
- WAN does DHCPv6 to get WAN IP (typically either a /64 or a /128)
- WAN does sepearate DHCPv6 to get a prefix delegation (e.g. /64, /60, /56)
- router assigns /64 prefixes from PD to LAN interface(s) as needed

So when you get a /60 via PD, that doesn't go on the WAN interface at
all, that's for use on LAN interfaces.

NM can get an apply a WAN IP in that setup just by setting
ipv6.method=auto.  There's some support in NM for also running PD and
assigning prefixes to LAN interfaces (although not sure it is in CentOS
8), but I think it's incomplete.  Instead, you can use something like:


to add event scripts to NM to handle it (although IIRC I had a couple of
issues with those scripts too, but didn't get back to working it all
Chris Adams <linux at cmadams.net>