The value of tmnxPortEtherDownWhenLoopedEnabled specifies whether physical loop detection for the Ethernet port is enabled or disabled. When enabled, the port will periodically send out keep-alive PDUs with an EtherType of 0x9000. If the port receives a keep-alive that it transmitted, tmnxPortState will be set to 'linkUp' if it was previously 'up'. The port will not move back to tmnxPortState 'up' for a period of time defined by tmnxPortEtherDownWhenLoopedRetry, but will continue to periodically send out keep-alive PDUs. Every time the port receives a keep alive it sent while a loop has been detected, it will reset the time period that it will remain down as defined by tmnxPortEtherDownWhenLoopedRetry.