[Kea-users] Seeking Guidance for Transitioning from Dnsmasq to Kea for DHCPv6 Multiple IP Assignments

[Furkan Sahin]

adding our team to CC (sorry)

On Tue, Sep 12, 2023 at 11:20 AM Furkan Sahin <furkan at ubicloud.com> wrote:

> Hello Kea Users,
>
> We've been using Dnsmasq to serve as our DNS cache, for router
> advertisement, and for DHCP functionalities. As Dnsmasq lacks support for
> prefix delegation, and we aim to serve both private and public IPv6
> prefixes, we are transitioning to a combination of Dnsmasq, radvd, and the
> Kea DHCP server.
>
> For the time being, we are focusing solely on assigning individual
> addresses with Kea, as we recognize that handling prefix delegation is more
> complex and currently unsupported by Netplan. This move is in preparation
> for future enhancements.
>
> Our key concern lies in the differing behavior between Dnsmasq and Kea in
> handling multiple IP assignments to the same client. In our setup, a single
> interface is configured with both a public and a private IPv6 prefix. When
> a DHCPv6 SOLICIT message is received, Dnsmasq automatically assigns
> multiple IP addresses based on the multiple dhcp-ranges configured for the
> interface. Kea, however, appears to assign only one IP address, choosing
> the subnet that is listed higher in the configuration.
>
> Is there a simpler way to achieve multiple IP assignments with Kea,
> similar to how Dnsmasq handles it? Is this a feature that could potentially
> be implemented in future releases of Kea?
>
> Additional Context on Our Setup:
>
> We are utilizing Cloud-Hypervisor to run VMs on a single server, with each
> VM isolated within its own network namespace.
> Each VM is managed by its own instance of Dnsmasq, radvd,
> kea-dhcp4-server, and kea-dhcp6-server.
> The VMs operate on Ubuntu 22.04 and utilize Netplan and systemd-networkd
> for network management.
> For further clarity, you can review my Pull Request that outlines our
> work: Ubicloud PR #564
> <https://github.com/ubicloud/ubicloud/pull/564/files#diff-c6f8b9419dfcf78ddc49be4e9515803f05a8fd2959463f39c5b9bcc6b9ff0ba0R370>
> .
>
> Your insights would be invaluable to us. Thank you in advance!
>
> Best regards,
> Furkan
>
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