This counter reports the IPv6 octets dropped from this queue because its total packet count exceeded the configured maximum threshold, i.e. a straightforward tail drop once the queue was full. It applies to a transmit queue on an interface where QoS queuing is enabled. It is the 64-bit version of eriRouterQosIfQueueIPv6TailDroppedOctets, used on high-traffic interface queues where a 32-bit counter could wrap between polls. Discontinuities in the value can occur when the management system re-initializes, so a sudden reset does not necessarily mean the underlying activity stopped.