[systemd-devel] systemd-networkd not sending DHCP v6 requests

[Mantas Mikulėnas]

On Tue, Jul 11, 2017, 22:24 Ian Pilcher <arequipeno at gmail.com> wrote:

> On 07/11/2017 02:58 AM, Lennart Poettering wrote:
> > Note that DHCPv6 is not done unless IPv6 RA packets tell networkd to
> > do so. Hence, areyou sure the RA spoken on your network properly
> > indicates that?
>
> Interesting.  I am seeing somewhat different behavior (but note that
> this is systemd-networkd 219 on CentOS 7, which is pretty old).
>
> * On networks with no router advertisements at all, systemd-networkd 219
>    will eventually send out dhcp6 solicit packets.
>
> * On a network with router advertisements that include prefix info
>    (option 3), systemd-networkd 219 will send dhcp6 solicit packets.
>
> * If the router advertisements on a network do not include any prefix
>    information, however, systemd-networkd 219 will never send any dhcp6
>    solicit packets and never configure an IPv6 address.
>
> Unfortunately, my ISP's router sends RAs without prefix information.
> (Clients get their addresses via DHCPv6, and are presumably expected to
> simply assume a 64 bit prefix length.)
>
> So it looks like I won't be able to use systemd-networkd to get around
> the dhclient wall clock problem, at least until RHEL/CentOS see an
> updated version of systemd (systemd-networkd 231 does seem to behave
> differently).
>

What global flags do each network's RAs have? If I remember correctly,
there are two, "Managed Addresses" and "Managed Other", which trigger
DHCPv6 – if neither of them is set, that is supposed to mean DHCPv6 is
unneeded.

>
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