To confirm the network connectivity of cluster elements, use either the rms_ip or rms_mac command to 'ping' individual elements.
For example, assume there is a COB board in slot 5 of the shelf named 'shasta'. To retrieve the IP address of cluster element 3 on that board, issue the following command:
rms_ip 3 5 shasta
A timeout, of course, indicates an issue with connectivity.