Users Guide

FEFD modes
FEFD operates in two modes—Normal mode and aggressive mode.
• Normal mode—When you enable Normal mode on an interface and a far-end failure is detected, no intervention is required to reset
the interface to bring it back to an FEFD operational state.
• Aggressive mode—When you enable Aggressive mode on an interface in the same state, you must manually reset the interface.
The following events explain how FEFD state transition occurs:
• When you enable FEFD on an interface a link transitions from idle state to unknown state.
• In the unknown state, the interface starts transmitting link state information at a regular interval. The interface state changes to bi-
directional when a handshake is complete with the peer.
• When an interface is in bi-directional state, if it does not receive an echo from its peer for the time interval of three times the
configured FEFD message interval, the interface state changes to unknown in Normal mode. In Aggressive mode, the interface state
changes to err-disabled.
If the interface state changes to err-disabled, use the fefd reset [interface] global command to reset these interfaces. The
unknown or err-disabled state brings the line protocol down so that the protocols above it can detect that the peer link is down.
Table 30. FEFD state changes
Local event
(User
intervention)
Configured
FEFD mode
Local state
(Show
display)
(Result)
Local admin
State
(Result)
Local line
protocol
Status
(Result)
Remote state
(Show
display)
(Result)
Remote
admin state
Remote line
protocol
status
Shutdown(user
configuration)
Normal Admin
Shutdown
Down Down Line protocol is
down.
Up Down
Shutdown(user
configuration)
Aggressive Admin
Shutdown
Down Down Line protocol is
down.
Up Down
FEFD+ FEFD
disable(user
configuration)
Normal Locally disabled Up Up Unknown Up Down
FEFD + FEFD
disable(user
configuration)
Aggressive Locally disabled Up Down Err-disabled Up Down
Link Failure
(Remove cable
or transceiver)
Normal Unknown Up Down Unknown Up Down
Link
Failure(Remov
e cable or
transceiver)
Aggressive Unknown Up Down Unknown Up Down
FEFD
enable(user
configuration)
Normal Bi-directional Up Up Bi-directional Up Up
FEFD
enable(user
configuration)
Aggressive Bi-directional Up Up Bi-directional Up Up
Restrictions
• You can enable FEFD globally or on an interface. If FEFD is enabled globally, the FEFD interface configuration overrides global FEFD
configuration.
• OS10 supports FEFD only on physical interfaces. FEFD is not supported on any other interfaces. However, you can enable FEFD on
individual physical interfaces that belong to a port channel.
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