Switching out a switch without taking down the office

Switch replacements in production make people nervous. They should not. Done right, the user-visible disruption is measured in seconds.

Preparation, the day before

• Pull the running config from the existing switch and translate it to the new one.
• Pre-stage the new switch on a bench. Apply the config. Verify it boots cleanly.
• Label every cable. If they are not labeled, label them now.
• Take photos of the front and back of the switch as it is currently cabled.
• Document a rollback plan that fits in three steps.

The day of

Schedule for low-traffic. Move cables one at a time, leaving the rest live. For each cable: unplug, plug into matching port on new switch, verify the link comes up. Patch panel labels make this trivial.

After

Update documentation. Capture the new running config. Confirm monitoring and management have rediscovered the new device.