Layer 2 | 637
FEFD state changes
FEFD has two operational modes, Normal and Aggressive. When Normal mode is enabled on an interface
an a far-end failure is detected, no intervention is required to reset the interface to bring it back to an FEFD
operational state.When Aggressive mode is enabled on an interface in the same state, manual intervention
is required to reset the interface.
FEFD enabled systems (comprised of one or more interfaces) will automatically switch between four
different states: Idle, Unknown, Bi-directional, and Err-disabled.
1. 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 packet
to the remote end of the link.
3. When the local interface receives the echoed packet from the remote end, the local interface transitions
to the Bi-directional state.
4. If the FEFD enabled system is configured to use FEFD in Normal mode and neighboring echoes are
not received after three intervals, (each interval can be set between 3 and 300 seconds by the user) the
state changes to unknown.
5. If the FEFD system has been set to Aggressive mode and neighboring echoes are not received after
three intervals, the state changes to Err-disabled. All interfaces in the Err-disabled state must be
manually reset using the
fefd reset [interface] command in EXEC privilege mode (it can be done
globally or one interface at a time) before the FEFD enabled system can become operational again.
Table 29-1. State Changes When Configuring FEFD
Local Event Mode Local State Remote State
Local
Admin
Status
Local
Protocol
Status
Remote
Admin
Status
Remote
Protocol
Status
Shutdown Normal Admin Shutdown Unknown Down Down Up Down
Shutdown Aggressive Admin Shutdown Err-disabled Up Down Up Down
FEFD enable Normal Bi-directional Bi-directional Up Up Up Up
FEFD enable Aggressive Bi-directional Bi-directional Up Up Up Up
FEFD + FEFD disable Normal Locally disabled Unknown Up Down Up Down
FEFD + FEFD disable Aggressive Locally disabled Err-disabled Up Down Up Down
Link Failure Normal Unknown Unknown Up Down Up Down
Link Failure Aggressive Err-disabled Err-disabled Up Down Up Down
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