The Adoption instructions should include guidance on how to configure the Podified Control Plane networking, and if needed reconfigure External Data Plane networking, so that combining the original data plane with the new control plane results in an operational cloud.

Specific areas of focus that should be made into stories:

• IP address management – what should the network config look like to avoid IPAM collisions between the data plane and the control plane. We need to consider that there may not be enough free IP addresses left in the original subnet ranges, the new control plane requires allocating more than the old control plane. We may support multiple approaches if desired (two are discussed in the doc below).
• Adoption of data plane nodes' NIC configs - how to configure EDPM so that the NIC configs are preserved. We want to minimize risk, but depending on the IPAM there may be new routes to add, and so we may need to re-run os-net-config.
• Connecting the new control plane to original isolated networks – if there is anything more to advise on beyond the IPAM and NIC config issues.

The epic's deliverable is meant to be primarily documentation, but if we come across things that can also be tested in the test suite/CI, we should do so too.

This epic should lay foundations for networking in general, but we're specifically interested in the IPv4 aspects. IPv6 will have its specifics around IPAM / subnets, so we track IPv6 environments under a separate epic OSPRH-883.

These problems were already brainstormed on at the November 2023 NG meetup, the following document contains solution ideas: https://docs.google.com/document/d/1ddw_RmD9w6nqOblVgNw-txQ5D1SgCaApNrYzZFTrI_8/edit

Acceptance criteria:

• Document the multiple ways available (not in detail, just high level)
• Helper documentation that helps human operators to translate director IPAM config to next-gen IPAM