One other question -- looks like SLAAC is working with the router-advert, but I believe Windows clients need DHCPv6 to receive addresses. I believe that the auto-config of DHCPv6 based on assigned prefix is not included yet, correct? Is that the 'Assisted' or 'Managed' modes that pfSense/Opnsense has?

Yup, sorry. Just figured that out too after reading https://blog.kylemanna.com/ipv6/using-native-ipv6-via-comcast-in-san-francisco/.

Appreciate it. Sorry, I had assumed VyOS was using dhclient, not DHCP6c.

In T421#64836, @c-po wrote:

sla-len should be 12 in your case then.

If that does not work, it could be that you need to hint comcast you want to have a /60 PD, by addin prefix ::/60 infinity; here into line 26

https://github.com/vyos/vyos-1x/blob/current/data/templates/dhcp-client/ipv6.tmpl#L26

or on the router itself you find the file here: /usr/share/vyos/templates/dhcp-client/ipv6.tmpl

In T421#63911, @c-po wrote:

From the Git commit:

commit faa85accc99d6ff777f12f5dd9e43a6dd8f7e7a2 (origin/ipv6-pd)
Author: Christian Poessinger <christian@poessinger.com>
Date:   Sun May 17 20:15:45 2020 +0200

    pppoe: dhcpv6-pd: T421: initial support

    The following configuration will assign a /64 prefix out of a /56 delegation
    to eth0. The IPv6 address assigned to eth0 will be <prefix>::ffff/64.
    If you do not know the prefix size delegated to you, start with sla-len 0.

      pppoe pppoe0 {
          authentication {
              password vyos
              user vyos
          }
          description sadfas
          dhcpv6-options {
              delegate eth0 {
                  interface-id 65535
                  sla-id 0
                  sla-len 8
              }
          }
          ipv6 {
              address {
                  autoconf
              }
              enable
          }
          source-interface eth1
      }

      vyos@vyos:~$ show interfaces
      Codes: S - State, L - Link, u - Up, D - Down, A - Admin Down
      Interface        IP Address                        S/L  Description
      ---------        ----------                        ---  -----------
      eth0             2001:db8:8003:400::ffff/64        u/u

This is a proof of concept. What is not working?

• IPv6 address is not removed from delegated interface
• router-advertisements? Not tested yet!