Network Operations · Topic 2 of 8
Lifecycle, Change and Configuration Management
Understand device life cycle with EOL and EOS, patching, change management steps, and configuration management with backups and golden baselines.
- 4 min
- EOL means the vendor stops selling. EOS means support and security fixes stop.
- Plan replacement before end of support, because unpatched devices become a security risk.
- Patches and firmware updates should be tested, scheduled and reversible.
What it is
Network equipment and software age, and every change to a network carries risk. Three related processes keep that under control: life cycle management, change management and configuration management.
Life cycle management plans when equipment is bought, updated and retired. Change management controls how changes are approved and made. Configuration management keeps track of what each device is supposed to look like.
How it works
Device life cycle
| Term | Meaning |
|---|---|
| End of life (EOL) | The vendor stops selling the product |
| End of support (EOS) | The vendor stops providing fixes, updates and technical support |
After end of support, new security flaws stay unpatched, so equipment should be replaced before that date. Tracking these dates in the inventory allows replacement to be budgeted ahead of time.
Software and firmware management
Updates fix bugs and security flaws. They apply to operating systems on servers and workstations, and to the firmware on switches, routers and access points.
Test updates first when possible, schedule them in a maintenance window and keep a way to go back. Applying patches on a regular schedule reduces the time a known flaw is open to attack.
Decommissioning
When a device is retired, remove it from monitoring and inventory, wipe its configuration and stored data, and dispose of it according to policy. Credentials and keys used by the device should be revoked or changed.
Change management
Change management is a formal process for making changes with the least disruption. Typical steps are shown below.
| Step | Purpose |
|---|---|
| Request a change | Describe what, why and who is affected |
| Analyze risk and impact | Identify dependencies and what could fail |
| Get approval | A change advisory board or manager signs off |
| Plan and schedule | Choose a maintenance window and notify users |
| Test and have a rollback plan | Confirm the change works and prepare a way to undo it |
| Implement | Make the change as planned |
| Validate and document | Check the result and update diagrams and records |
An emergency change follows a shorter path when an outage or serious security issue must be fixed at once, but it is still documented after the fact.
Configuration management
Configuration management records and controls the settings of devices.
| Term | Meaning |
|---|---|
| Production configuration | The configuration currently running on a device |
| Backup configuration | A saved copy that can be restored after a failure or mistaken change |
| Baseline or golden configuration | An approved standard configuration used as a reference for new or existing devices |
A golden configuration lets a technician build a replacement device quickly and consistently. Configuration drift is when a device slowly deviates from the approved baseline because of unrecorded changes, and regular comparison against the baseline finds it.
Back up configurations before and after each change, and keep copies off the device. Store them securely, because they contain sensitive information.
What to remember for the exam
- EOL means the vendor stops selling. EOS means support and security fixes stop.
- Plan replacement before end of support, because unpatched devices become a security risk.
- Patches and firmware updates should be tested, scheduled and reversible.
- Decommissioning includes wiping data, updating inventory and revoking credentials.
- Change management steps: request, impact analysis, approval, schedule, test with rollback, implement, validate and document.
- A rollback plan is required so a failed change can be undone.
- A golden configuration is the approved baseline. Configuration drift is deviation from it.
- Keep backup configurations before and after changes.
If an exam asks what to do before making a risky change, look for the answer that includes a backup of the configuration and a rollback plan.
Common mistakes
Confusing EOL and EOS. EOL is the end of sales. EOS is the end of support and fixes, and it is the one that creates risk.
Skipping the rollback plan. Without a way to undo a change, a failure becomes an outage.
Making emergency changes without documentation. Even urgent changes must be recorded afterward.
Treating backup configurations as a one time task. They go stale, so save a new copy after each approved change.
Forgetting to update diagrams after a change. Documentation drift causes problems later.
Changing a production device without approval, even to fix a small problem, can cause an outage elsewhere. Follow the process unless it is a documented emergency.
Check yourself
Try these three.
What is the difference between EOL and EOS?
EOL means the vendor stops selling the product, and EOS means it stops providing support and security fixes.
What must every change include so it can be undone?
A rollback plan, along with a current backup of the configuration.
What is a golden configuration?
An approved baseline configuration used as the reference for building and checking devices.
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