Upgrading Two Controllers in Availability Mode

This section, which describes how to upgrade the software version on two controllers in availability mode, is applicable if the availability pair is made of one of the following combinations:

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Availability Pairs

Controller 1 Controller 2
C25 C25
C35 C35
C4110 C4110
C5110 C5110
C5210 C5210
C5215 C5215
V2110 V2110


The two wireless controllers in an ‘availability‘ pair must be running the identical version of the software.

For the ease of understanding, this section is explained with the help of the following hypothetical scenario:

  • The upgrade is to be carried out on the two controllers — EWC-1 and EWC-2.
  • Both the controllers are operating in ‘availability‘ mode.
  • Both controllers are running the previous software release, and they need to be upgraded to the next software release.
  • Each controller has two APs. EWC-1 has AP-1 and AP2, whereas EWC-2 has AP-3 and AP-4.
  • AP-1 and AP-2 are configured as ‘Local‘ on EWC-1 and ‘Foreign‘ on EWC-2.
  • AP-3 and AP-4 are configured as ‘Local‘ on EWC-2 and ‘Foreign‘ on EWC-1.

The following figure depicts the hypothetical upgrade process:

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The Upgrade Process for Two Controllers in Availability ModeGraphics/AvailabilityPair_SW_upgrade_10_1.png