Backbone link cutover, module batch shifting, and device port migration all depend on the change window. The window is not the construction buffer time, but the time when verification must be completed. The most commonly ignored item in the plan is the fallback condition and rollback time.

The window length is reversed according to the time consumption.

A common mistake is to estimate the window based on the construction time: if welding takes two hours, only apply for two hours. A reasonable algorithm is construction time plus verification time, plus a complete rollback time. Because rollback is often slower than construction, port correspondence and jumper labels need to be rechecked. A 30-minute static observation period is left at the end of the window to confirm that there is no intermittent packet loss before calling it a day. This algorithm will take some time to explain to the business side for the first time, but it is much cheaper than temporary coordination after timeout. EB-LINK technical support usually gives suggestions based on this caliber when assisting in arranging windows.

Six preparations before cutover

• The port and fiber core correspondence table is printed on the wall. Do not rely on the screenshots on your mobile phone, as the on-site signal often cannot be transmitted.
• Spare parts are in place and powered on in advance, including modules of the same grade, test jumpers and14-slot box transceiver rackspare slot.
• The meter has sufficient power and is within the calibration period. A set of optical power meters and test jumpers are provided.
• The baseline readings are copied in advance, and there will be a comparison target on site after the cutover, so there is no need to guess temporarily.
• The business party confirms the off-peak period and agrees on verification use cases and the responsible persons of both parties.
• Specify the triggering conditions for the rollback, for example, if there is no light for 30 minutes after the scheduled time, the rollback will be initiated.

Verification does not look at the indicator light, look at the data

The light on the link only indicates that there is light and cannot be used as a basis for completion. At least three things must be confirmed: the light collection falls near the baseline and the margin is no less than 3 dB, the error frame count does not increase during the observation period, and the business side runs through the agreed use cases. High-speed links need to be checked100G DAC high speed cableThe slot definition and negotiated speed at both ends prevent the link from being ignored when running at reduced speed. All data is archived into a change order, and this page should be turned before the next round of changes.