Document what already works
An upgrade begins with an asset and service map, not a complete replacement assumption. Collect models, versions, physical ports, addressing and current operating issues without including passwords.
- Switch/AP/ONU models and active license/support status.
- Copper certification, fiber type/loss and actual routes.
- Current VLANs, gateway rules, DHCP/DNS, voice, multicast and application dependencies.
Create a retain / replace / add schedule
Relate every new device to an existing zone and a reason for change. Keep temporary links and migration hardware distinct from the final BOM.
- Retain compliant cabling and compatible endpoints where practical.
- Replace capacity/power/environment bottlenecks backed by measured evidence.
- Add missing coverage, spare ports, backup power or approved failover paths.
Prove one zone before scaling
Agree the outage and rollback trigger with the building operator. A successful link light is not full service acceptance.
- Test staff/guest authentication, phone registration and call quality.
- Verify CCTV recording/playback, IPTV channel change and multicast boundaries.
- Record configurations, labeled ports and rollback steps before the next floor.