Netplan has no option to enable dhcpv6 prefix delegation like ifupdown did

Bug #1771886 reported by Bryce Larson on 2018-05-17
This bug affects 20 people
Affects Status Importance Assigned to Milestone

Bug Description

When using ifupdown, you can put 'request_prefix 1' in order to specify for dhclient to request an dhcpv6 prefix delegation. I also understand that systemd-networkd also supports this, see If netplan is to fully replace ifupdown feature for feature, it needs to support this functionality as I am using that feature with ifupdown and cannot upgrade to netplan without it.

I understand from the website that you guys want cases like this to be reported here. Let me know if that is not the case or if there is a better place to put things like this.

Bryce Larson (bryceml) wrote :

Another thing that relates to this is the ability to specify what the duid is that is sent in the dhcpv6 request. If I recall correctly systemd-networkd offers the ability to specify the duid.

Ryan Harper (raharper) wrote :

Hi Bryce,

Thanks for taking the time to report this issue.

netplan doesn't yet support setting dhcpv6 prefix delegation. Thanks for the link.

The relevant networkd sections are available and documented here:


[IPv6PrefixDelegation] Section Options

We'll need to see what, if any support for this there is in NetworkManager and then determine what key/values to use to control and then add support to the backend renders.

W.r.t the DUID, networkd currently sends an RFC4361-compliant Client ID, which is the combination of IAID and DUID; this is generated automatically by systemd. If you need to override this value currently you need to create a global override to /etc/systemd/network.conf, details here.

That's not currently modeled in the yaml or backends either.

Changed in netplan:
status: New → Confirmed
Wladimir Mutel (mwg) wrote :

1 year has definitely passed since the release of Ubuntu 18.04
netplan had been updated through 0.36 -> 0.40 -> 0.97 -> 0.98
any progress in supporting dhcp6-pd there ???

John Ioannidis (ubuytu) wrote :

It's now 2020. I really have to ask: who writes networking software, let alone making it the default, and does not consider fully-supporting IPv6 a requirement?

John Ioannidis (ubuytu) wrote :

When will this be fixed? Why was netplan made the default when it does not have feature parity with ifupdown? Why is this question being ignored?

Konstantin Novitsky (novitk) wrote :

Gave up on Ubuntu in a router/network appliance space due to this. Sure, I can remove netplan and use ifupdown, but why bother when openwrt just works!

Wladimir Mutel (mwg) wrote :

Fortunately, with systemd-networkd + wpa_supplicant you could go without any of {netplan, ifupdown, NetworkManager} on both modern Ubuntu or modern Debian. As you may imagine, netplan is just a frontend generating ("rendering") configs for one of possible backends within {networkd, NetworkManager}. So you just copy /run/systemd/network/* into /etc/systemd/network/ , after which you may remove all netplan and related packages and go ahead with systemd-networkd only (which, unfortunately, is nailed to the core of modern Linuxes pretty firmly and not that easily detachable).

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