If two Adaptive Session Redundancy (ASR) redundant Content Services Switches (CSS) peers run WebNS versions, where one includes the fix for defect CSCdy19162 (registered customers only) , and one does not, the backup box would not see any dormant flows, therefore, during a failover all of the ASR flows would fail.
A fix for defect CSCdy19162 (registered customers only) was introduced into 7.10.3.05 and 7.20.1.04, which broke ASR communication between systems running WebNS prior to these versions. The ASR backup CSS is no longer able to receive and interpret the messages about the dormant flows, which causes ASR to fail.
If two CSSs in a redundant ASR scenario run different versions, where one is prior to 7.10.3.05 or 7.20.1.04 and the other is running 7.10.3.05 or higher or 7.20.1.04 or higher, then in the case of a failover, the ASR will fail. The dormant flows will not get setup on the backup CSS and therefore all sessions will be lost on failover.
If you would like to use the ASR feature, then have both CSSs run WebNS 7.10.3.05 or higher or 7.20.1.04 or higher.
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