MRV Communications EM316SW-XY - Manual (Page 11)

Fiber Driver
®
EM316SW-XY
PN 1288003-001, Rev D2
3
2.1.2 Link Integrity Notification (LIN)
LIN is not available in switch mode.
A single DIP switch (LIN EN) activates LIN for the entire module except in switch mode. If this
switch is OFF, then LIN cannot be activated even through software management. In the other
operational modes, ports on the EM316SW-XY are paired as converters or repeaters. LIN
applies to each port pairing with mode considerations noted in the corresponding sections. In
Redundant Link mode, changing LIN status on any port adjusts all ports (P1, P2, and P3) to the
same setting. Port P4 is disabled in this mode.
When a link fault is detected on a paired port, LIN shuts down the transmitter on the partner port
to notify connected equipment dependent the lost link. This status propagation allows switches,
routers, and other link-state dependant devices to accurately react to link conditions.
With standard LIN operation (without FEFI), digital diagnostics traps are suppressed. The LED
indicates beaconing with regular flashes while a link is down and data activity with irregular
flickers otherwise. A beaconing port is considered to have no signal.
LIN is especially valuable in fault-tolerant designs.
2.1.3 LIN with Far End Fault Indication (FEFI)
The SFP ports support FEFI, which conforms to IEEE 802.3u 100BASE-FX specifications.
When an SFP port detects a link failure on its receiver, it sends an FEFI (Far End Fault
Indication) signal to the remotely connected device as notice of a link fault. It may also receive
an FEFI signal sent from the remote link partner, which causes it to disable the paired copper
Ethernet port transmitter.
FEFI is always enabled on the EM316SW-XY, but it is used only as requested by LIN and
configured through either DIP switches (FEFI and FEFI2) or management module
administration.
In Redundant Link mode, enable both FEFI DIP switches (FEFI=ON and FEFI2=ON) to use
FEFI with LIN. This configuration provides “1:1” link protection to the redundant link. The dual-
homing configuration (separate remote optical devices) is not supported.
2.1.4 Redundancy
The EM316SW-XY redundant mode (discussed in the following section) pairs the two SFP ports
(P2 and P3) as a self-healing link based on signal detection. The switch-over time when the
active fiber link fails is very short, which can allow transparent failover.
LIN disables the Ethernet port P1 only if BOTH fiber channels fail simultaneously. Port P4 is
disabled in redundant mode.