Notes from the operations side of ISP and media platforms.
Checklists and topologies I actually use: ACS migrations, CAS entitlement reconciliation and high-availability front-ends for RADIUS and billing. Written for the people who get paged.
RADIUS is UDP, billing is HTTP and the database is a cluster. One pair of front-end nodes running keepalived and HAProxy can keep all three online if you split the roles correctly. The topology, the checks and the failure drills.
A staged, checklist-driven way to move routers and ONTs from a vendor ACS to GenieACS: inventory, presets per model, batch-wise ACS URL changes, verification gates and a rollback that is just a URL.
Entitlement drift between your subscriber management system and the CAS is a retry and reconciliation problem, not a vendor problem. Here is where drift comes from and the loop that keeps Nagra, SafeView or ABV in step with billing.