ADR 0025 — Hyper-V network-management authority
Status: Accepted
Date: 2026-08-12
Decision owners: Repository owner and maintainers
Context
ADR 0021 separated the Hyper-V and Azure Local platform tracks, but its context treated Network ATC as part of the Azure Local-specific distinction. Network ATC is also supported for eligible Windows Server 2025 Datacenter failover clusters. It is therefore a Hyper-V topology and monitoring concern, not an Azure Local-only capability.
Hyper-V environments can instead use manually managed host networking or select SCVMM and Windows Server Software Defined Networking as the network-management authority. The Management Pack must discover the active model and avoid assuming that every cluster is owned by Network ATC.
Decision
Use Network ATC as the preferred host-networking baseline for eligible Windows Server 2025 Datacenter Hyper-V failover clusters. When SCVMM and Windows Server SDN are the selected network-management authority, model and monitor that path instead of assuming Network ATC ownership. Treat standalone, older, ineligible, and manually managed networking as explicit support matrix variants. Discovery and monitoring must identify the applicable authority without enforcing or changing host-network configuration.
This decision supersedes only the implication in ADR 0021 that Network ATC differentiates Azure Local from Hyper-V. The platform-first and delivery-surface architecture in ADR 0021 remains accepted.
Consequences
- Eligible Hyper-V clusters receive Network ATC intent, deployment, status, and drift research.
- SCVMM/SDN-managed environments require their own discovery and health evidence.
- The support matrix must state which non-ATC configurations are supported.
- The MP must not create conflicting network-management ownership or remediate configuration.
- Research must validate supported combinations and stable monitoring sources before successor discovery and signal ADRs are accepted.
Alternatives considered
Treat Network ATC as Azure Local-only
Rejected because it omits a supported and preferred Windows Server 2025 cluster networking model.
Require Network ATC for every Hyper-V deployment
Rejected because standalone, older, ineligible, manually managed, and SCVMM/SDN environments need an explicit support decision.
Monitor Network ATC and SCVMM/SDN simultaneously without authority detection
Rejected because overlapping assumptions can produce misleading health and conflicting ownership.