Learn about the Distributed Compute Node (DCN) adoption so you can prepare your environment and avoid errors.

The process to adopt the DCN deployment from Red Hat OpenStack Platform (RHOSP) to Red Hat OpenStack Services on OpenShift (RHOSO) requires additional adoption tasks:

• You must map a multi-stack deployment to multiple node sets.
• You must map additional networking configurations.

  Multi-stack to multi-node set mapping

  In director deployments, DCN environments use multiple Heat stacks:

  • The Central stack is templating for Controllers and central Compute nodes.
  • An edge stack is templating for Edge Compute nodes in a stack. There is one stack per DCN site.

    When you perform an adoption, map director stacks to OpenStackDataPlaneNodeSet custom resources (CRs):

    Table 1. Mapping director stacks to RHOSO node sets

    director stack	RHOSO node set	Availability zone
    Central stack (Compute role)	openstack-edpm or openstack-cell1	az-central
    DCN1 stack (ComputeDcn1 role)	openstack-edpm-dcn1 or openstack-cell1-dcn1	az-dcn1
    DCN2 stack (ComputeDcn2 role)	openstack-edpm-dcn2 or openstack-cell1-dcn2	az-dcn2

    Note

    Keep all node sets in the same Nova cell to maintain unified scheduling through a shared cell. The default cell is cell1.

  Key differences from standard adoption

  The following table summarizes the differences between standard adoption and DCN adoption:

  Table 2. Comparison of standard and DCN adoption

  Aspect	Standard adoption	DCN adoption
  Director stacks	Single stack	Multiple stacks (central + edge sites)
  Network topology	Flat L2 networks	Routed L3 networks with multiple subnets
  Data plane node sets	Single node set	Multiple node sets (one per site minimum)
  Network routes	Usually not required	Required for inter-site connectivity
  Physnets	Single physnet (e.g., datacentre)	Multiple physnets (e.g., leaf0, leaf1, leaf2)
  Availability zones	Often single AZ	Multiple AZs (one per site)
  OVN bridge mappings	Single mapping	Site-specific mappings
  Provider networks	Single segment	Multi-segment routed provider networks

  Requirements for DCN adoption

  Before adopting a DCN deployment, ensure you have:

  • Network topology information for all sites (IP ranges, VLANs, gateways)
  • Inter-site routing configuration (routes between site subnets)
  • Mapping of director roles to availability zones
  • OVN bridge mapping configuration for each site

DCN Adoption workflow overview

The adoption of a Distributed Compute Node (DCN) deployment from Red Hat OpenStack Platform (RHOSP) to Red Hat OpenStack Services on OpenShift (RHOSO)

1. Control plane adoption: Adopt all control plane services from the central director stack to the RHOSO control plane. This is identical to standard adoption.
2. Network configuration: Configure multi-subnet NetConfig and NetworkAttachmentDefinition CRs to support all site networks.
3. Data plane node set creation: Create separate OpenStackDataPlaneNodeSet CRs for each site, each with site-specific network configurations:
   • Network subnet references
   • OVN bridge mappings (physnets)
   • Inter-site routing configuration
4. Data plane deployment: Deploy all node sets. The edge site node sets can be deployed in parallel after the central site control plane is adopted.