If you see any VCSIPC errors in the Oracle trace/log files, check /var/adm/messages for any LMX error messages. If you see messages that contain any of the following:
See About LMX tunable parameters
If you see any VCSIPC warning messages in Oracle trace/log files that resemble:
Reporting communication error with node
check whether the Oracle Real Application Cluster instance on the other node is still running or has been restarted. The warning message indicates that the VCSIPC/LMX connection is no longer valid.