System functionalities
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In this chapter you will learn about:
- Upgrade with CRC check

Description
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The upgrade process have been modified for robustness.
When the unit is booted the CRC is calculated and checked for Primary and Secondary image in there partitions in flash, this takes around 15-20 seconds.
If an Upgrade have succeeded downloading a new firmware and started erase/program in flash a new CRC is calculated and checked as above when the upgrade has finished.
If the Upgrade fails before the erase/program in flash is started the new CRC calculation and check will not be started.
The support for checking the CRC is used in CLI and WEB when upgrading primary and secondary image:
   In CLI:
      -If the Secondary image in flash have 'Invalid CRC' there will be a question, when upgrading Primary image, if you are sure you would like to do this.
      and 
      -If the Primary image in flash  have 'Invalid CRC' there will be a question, when upgrading Secondary image, if you are sure you would like to do this.
      -If an calculation and check of the CRC is in progress the message will be 'Calculates CRC'.

   In WEB:
      -The logic above will be the same in web with a page presenting a checkbox to ignore the Invalid CRC/Calculates CRC and continuing upgrade.
      
The CRC information is also shown in CLI and WEB system information/details.
   -The Primary Firmware/Secondary Firmware version parameter is extended with the status of the CRC check inside parenthesis.
