Core Network Switch Firmware Patching — Admin Tower
·Maintenance Summary
Critical security and stability firmware patches will be applied to the three Cisco Catalyst core distribution switches serving Admin Tower on Saturday, April 5, 2026 from 10:00 PM to 11:30 PM.
Patching follows a rolling restart approach: one switch is patched and verified before proceeding to the next, minimising the outage window.
Patch Details
| Switch | Model | Current Firmware | Target Firmware | CVE Addressed |
|---|---|---|---|---|
| SW-ADMIN-CORE-01 | Catalyst 9300 | 17.9.3 | 17.12.2 | CVE-2025-20388, CVE-2025-21541 |
| SW-ADMIN-CORE-02 | Catalyst 9300 | 17.9.3 | 17.12.2 | CVE-2025-20388, CVE-2025-21541 |
| SW-ADMIN-DIST-01 | Catalyst 9200 | 17.9.2 | 17.12.1 | CVE-2025-21541 |
Expected Impact
| Phase | Time | Impact |
|---|---|---|
| SW-ADMIN-CORE-01 patch & restart | 10:00–10:25 PM | Wired connectivity on floors 1–3 interrupted ~3 min |
| SW-ADMIN-CORE-02 patch & restart | 10:30–10:55 PM | Wired connectivity on floors 4–6 interrupted ~3 min |
| SW-ADMIN-DIST-01 patch & restart | 11:00–11:20 PM | Distribution-layer failover; minimal interruption expected |
| Final validation | 11:20–11:30 PM | No interruption |
- Wireless (Wi-Fi) access in Admin Tower will be briefly impacted during each switch restart as APs re-associate.
- V oIP phones will need to reboot automatically after each phase — calls should not be attempted during the switch restart windows.
- Off-campus VPN traffic for Admin Tower users is not affected.
Pre-Maintenance Checklist
- Firmware images downloaded and checksums verified
- Configuration backups taken for all three switches
- Change ticket approved by Change Advisory Board
- Network Operations on-site; Network Manager on call
- Out-of-band OOBM access verified (Console server
oob-admin.example.edu)
Rollback Plan
If a switch fails to boot on the new firmware, the previous firmware version is retained in the inactive partition. Rollback requires setting the boot variable and restarting the switch (approximately 8 minutes per device).
Contacts
For issues during this maintenance window: Network Operations on-call — ext. 5556 or net-ops@example.edu.
