Reference Guide

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, (you can set each interval can be set between 3 and 300 seconds) 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. 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 33. 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
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
Important Points to Remember
● You can enable FEFD globally or on a per-interface basis. Interface FEFD configurations override global FEFD configurations.
● The system supports FEFD on physical Ethernet interfaces only, excluding the management interface.
Configuring FEFD
You can configure FEFD for all interfaces from CONFIGURATION mode, or on individual interfaces from INTERFACE mode.
To enable FEFD globally on all interfaces, use the following command.
● Enable FEFD globally on all interfaces.
CONFIGURATION mode
fefd-global
To report interval frequency and mode adjustments, use the following commands.
1. Setup two or more connected interfaces for Layer 2 or Layer 3.
INTERFACE mode
ip address ip address, switchport
2. Activate the necessary ports administratively.
INTEFACE mode
no shutdown
3. Enable fefd globally.
CONFIGURATION mode
452
Layer 2