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Configuring Interfaces
Monitoring and Maintaining the Interfaces
Using FEFI to Maintain the Fiber FE Interfaces
A far end fault is an error in the link that one station detects but the other does not, such as a disconnected Tx wire. In
this example, the sending station still receives valid data and detects that the link is good through the link integrity
monitor. The sending station does not detect that its own transmission is not being received by the other station. A
100BASE-FX station that detects a remote fault like this modifies its transmitted IDLE stream to send a special bit pattern
(FEFI IDLE pattern) to inform the neighbor of the remote fault. The FEFI-IDLE pattern then triggers a shutdown of the
remote port (notconnect).
Fiber FastEthernet hardware uses far end fault indication (FEFI) to bring the link down on both sides of the link in these
situations. A similar function is provided by link negotiation for Gigabit Ethernet. FEFI is not supported on copper ports,
which do not usually have issues in which one station can detect while the other cannot. Copper ports use Ethernet link
pulses to monitor the link.
With FEFI, no forwarding loop occurs because there is no connectivity between the ports. If the link is up on one side
and down on the other, however, blackholing of traffic might occur. Use Unidirectional Link Detection (UDLD) to prevent
traffic blackholing.
Default FEFI Configuration
FEFI is enabled globally and not configurable on the switch, however it applies only to the fiber Fast Ethernet SFP
interfaces on the switch.
show interfaces [interface-id] transceiver [detail |
dom-supported-list | module number | properties
| threshold-table]
Display these physical and operational status about an SFP module:
interface-id–(Optional) Display configuration and status for a
specified physical interface.
detail–(Optional) Display calibration properties, including high and
low numbers and any alarm information for any Digital Optical
Monitoring (DoM)-capable transceiver if one is installed in the
switch.
dom-supported-list–(Optional) List all supported DoM
transceivers.
module number–(Optional) Limit display to interfaces on module
on the switch. The range is 1 to 9. This option is not available if
you entered a specific interface ID.
properties–(Optional) Display speed, duplex, and inline power
settings on an interface
threshold-table–(Optional) Display alarm and warning threshold
table
show interfaces [interface-id] [{transceiver
properties | detail}] module number]
Display physical and operational status about an SFP module.
show port-type [eni | nni | uni] Display interface type information for the Cisco ME switch.
show running-config interface [interface-id] Display the running configuration in RAM for the interface.
show version Display the hardware configuration, software version, the names and
sources of configuration files, and the boot images.
show controllers ethernet-controller interface-id
phy
Display the operational state of the auto-MDIX feature on the
interface.
Table 8 Show Commands for Interfaces (continued)
Command Purpose
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