The iSCSI node index for this member node entry. This
index is used to uniquely indicate this table entry,
and provides a 1 to 1 mapping to the node name in
cIsnsDdMemberIscsiName. The iSCSI node name is too long
to be used for an index directly. The iSCSI node index
used for a specific iSCSI node name MUST be identical
in all DDs and control node registrations, and is
persistent across server reinitializations when the
iSCSI node is a member of a Discovery Domain (DD) or is
registered as a control node. The managed object
cIsnsNextIdxUnregIscsiNodeInDd is used to determine an
available index when an unregistered iSCSI node is to be
added to a Discovery Domain prior to it being registered
in the server using the iSNS protocol.