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

[Furkan Sahin]

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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