# Underlay Mode

Programs the actual physical network fabric via vendor SDK dispatch through Bascule. Used for sites where you own the infrastructure.

## Components
- VLAN interface manager (`internal/vlan/`)
- YANG watcher and compilation trigger (`internal/underlay/`)
- YANG compiler (`yang/compiler/`)
- NetworkMutationArtifact notarization (`internal/quartermaster/`)

## YANG Pipeline
1. YANG instance data changes (ConfigMap/CRD)
2. Watcher triggers compilation
3. Compiler produces vendor-specific payloads (FortiOS, VyOS, UniFi)
4. Payloads dispatched via Bascule SDK
5. Each mutation notarized via Quartermaster