Layer 2 | 5371. An interface on which FEFD is not configured is in Normal mode by default.2. Once FEFD is enabled on an interface, it transitions to the Unknown state and sends an FEFD packetto the remote end of the link.3. When the local interface receives the echoed packet from the remote end, the local interface transitionsto the Bi-directional state.4. If the FEFD enabled system is configured to use FEFD in Normal mode and neighboring echoes arenot received after three intervals, (each interval can be set between 3 and 300 seconds by the user) thestate changes to unknown.5. If the FEFD system has been set to Aggressive mode and neighboring echoes are not received afterthree intervals, the state changes to Err-disabled. All interfaces in the Err-disabled state must bemanually reset using the fefd reset [interface] command in EXEC privilege mode (it can be doneglobally or one interface at a time) before the FEFD enabled system can become operational again.Important Points to Remember• FEFD enabled ports are subject to an 8 to 10 second delay during an RPM failover before becomingoperational.• FEFD can be enabled globally or on a per interface basis; interface FEFD configurations overrideglobal FEFD configurations.• FTOS supports FEFD on physical Ethernet interfaces only, excluding the management interface.Configuring FEFDYou can configure FEFD for all interfaces from CONFIGURATION mode, or on individual interfacesfrom INTERFACE mode.Enable FEFD GloballyTo enable FEFD globally on all interfaces enter the command fefd-global in CONFIGURATION mode.Table 24-1. State Changes When Configuring FEFDLocal Event Mode Local State Remote StateLocalAdminStatusLocalProtocolStatusRemoteAdminStatusRemoteProtocolStatusShutdown Normal Admin Shutdown Unknown Down Down Up DownShutdown Aggressive Admin Shutdown Err-disabled Up Down Up DownFEFD enable Normal Bi-directional Bi-directional Up Up Up UpFEFD enable Aggressive Bi-directional Bi-directional Up Up Up UpFEFD + FEFD disable Normal Locally disabled Unknown Up Down Up DownFEFD + FEFD disable Aggressive Locally disabled Err-disabled Up Down Up DownLink Failure Normal Unknown Unknown Up Down Up DownLink Failure Aggressive Err-disabled Err-disabled Up Down Up Down
