The value of this object defines how this X25 MLP logical port may use additional ISDN-B channel to transmit temporary excess traffic (overflow mechanism). When opening or closing additional B-Channels the existing VCs are not cleared, so this overflow mechanism does not alter the communication between the two extremities. The possible values are : off : overflow is never enabled, onSlave : overflow is enabled by the connected equipment, onMasterWhileActivity : when the traffic overtakes the fclX25MlpOvOverflowThreshold value for all the links in use (line interfaces and eventual ISDN B-Channels), a new ISDN B-Channel is open by the equipment and remains active while at least one X25 VC is using this way. When no VC is active, this ISDN B-Channel is closed. onMasterWhileExcessTraffic : when the traffic overtakes the fclX25MlpOvOverflowThreshold value for all the links in use (line interfaces and eventual ISDN B-Channels), a new ISDN B-Channel is open by the equipment and remains active while the traffic is overtaking the fclX25SlpOvOverflowBackThreshold value. When the traffic does not overtake any more the fclX25SlpOvOverflowBackThreshold value, this ISDN B-Channel is closed. When one line interface is DOWN its bandwith is considered as being 0. So the overflow mechanism may be used as a backup mechanism which permits to not clear existing VCs. The default value is 'off'.