Administrator Guide

FEFD State Changes
FEFD has two operational modes: Normal and Aggressive.
When a far-end failure is detected on an FEFD-enabled interface:
● If the interface is in normal FEFD mode, no user intervention is required to reset the interface; it automatically resets to an
FEFD operational state.
● If the interface is in aggressive FEFD mode, manual intervention is required to reset the interface.
FEFD-enabled systems consist of one or more interfaces, which automatically switch between four states: Idle, Unknown, Bi-
directional, and Err-disabled.
1. An interface on which FEFD is not configured is in Normal mode by default.
2. After you enable FEFD 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, the state changes to unknown. You can set each interval from 3 to 255 seconds.
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. You must manually reset all interfaces in the Err-disabled state 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 48. State Change 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
Unknown 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 Up Up Down
Link Failure Normal Unknown Unknown Up Down Up Down
Link Failure Aggressive Unknown Unknown Up Down Up Down
Important Points to Remember
● FEFD is supported only on physical Ethernet interfaces, except the management interface.
● FEFD is not supported on copper Ethernet and Fibre Channel ports. FEFD is supported only on fiber Ethernet ports.
● FEFD is not supported on port extender (PE) ports.
● FEFD is not supported on port-channels or port-channel members.
● You can enable FEFD globally or on a per-interface basis. Interface FEFD configurations override global FEFD configurations.
Configuring FEFD
You can configure FEFD on all interfaces from CONFIGURATION mode or on individual interfaces from INTERFACE mode.
To enable FEFD globally on all interfaces, use the following command.
● CONFIGURATION mode
Layer 2
541