B&B Electronics 855-12665-82 User Manual

Link Fault Pass-Through (LFPT)

Posted date: Dec. 22, 2008
Doc Number: TB2008DEC19

LFPT is a troubleshooting feature that combines TX and FX LinkLoss from both the
local and remote IMC devices. This feature, when enabled, will pass a link fault through
the device at each segment. Therefore, if a link fails on one side of the media converter,
the media converter will force the link down on its link partner. LFPT can be enabled via
DIP Switches or SNMP management (if the product supports it). When enabled, the TX
LL and FX LL LEDs glow green; when a fault occurs on a particular segment, the LEDs
will blink.

In the example below, note that only the switches are being monitored with SNMP Traps.

If a fault should occur on the fiber (Segment 2) without LFPT enabled, both switches
would remain linked to the media converters even though a link has failed between the
media converters. Since neither switch would sense a failed link they would not send out
a Trap.

When LFPT is enabled and a fault occurs on the Fiber Segment (Segment 2), both media
converters would pass that fault through to the next segment. Media Converter 1 would
force the Copper Segment 1 down which Switch 1 would sense and it would send out a
Trap. Media Converter 2 would force Copper Segment 3 down which Switch 2 would
sense and it would send out a Trap. The SNMP server would receive the Traps and take
the appropriate actions to help remedy the issue (usually by sending an alert to the
network administrator). If a single fault occurs, all Link LEDs will extinguish. To help
isolate where a fault occurs, a “BLINK” function has been implemented for the TX LL
and FX LL LED indicator. This identifies the source of the fault under all conditions.
LFPT will be implemented on further IMC devices; refer to each product manual for
details.

LFPT is currently available on the following IMC Network products: McGigabit*, iMcV­Gigabit, iMcV-FiberLinX-II, iMcV-GigaFiberLinX-II, and IE-Mini-FiberLinx-II.

12/22/2008

Note: When configuring multiple IMC conversion devices, the LFPT feature is only
operationally available using IMC devices that include the LFPT feature (mentioned
above). *unmanaged

12/22/2008