The value of tmnxEthRingPathIfIndex specifies the member's port
tmnxPortPortID associated with the tmnxEthRingConfigEntry.
This object must be included in the same SNMP PDU as that of the
tmnxEthRingPathRowStatus object for creation of the path. The absense
of this object will result in a NO CREATION error.
The tmnxEthRingPathIfIndex can not be changed; the row must be
destroyed and re-created.