The value of tmnxEthRingSubRingPropTopChange specifies whether or not
the Ethernet sub-ring propagates topology changes to the interconnected
ring as specified by the value of tmnxEthRingSubRingInterconnectId.
Attempts to modify this object away from its default value when
tmnxEthRingSubRingInterconnectId is set to zero (0) will result in an
SNMP inconsistentValue error.