11
Auto Laser Shutdown
Automatic Laser Shutdown (ALS) is a technique used to
automatically shut down the output power of the fiber transmitter in
case of fiber break according to ITU-T G.664. This is a safety feature that
prevents dangerous levels of laser light from leaking out of a broken
fiber, provided ALS is provisioned on both ends of the fiber pair. The
sequence of events is as follows. If a fiber is cut, the receiver will detect
a Loss Of Signal (LOS). The ALS agent will turn off the transmitter. The
receiver at the far end will then detect an LOS and its ALS agent will turn
off the transmitter. In this way the entire fiber will go dark.
Client Side Loopback Test (LBT) Function
The loopback capability of FRM220-TM-10GMux is useful for
debugging a dysfunctional SFP link (CH1
~
CH7). In loopback mode, the
signal is routed into the Cross Switch circuitry and then routed back to
the signal source. Loopback may be enabled via management terminal
console. When placed in a managed FRM220-CH20 or CH08 chassis, the
loopback test function can also be controlled by the NMC manager in
FRM220 chassis.
In the example below, when the loopback test function is enabled
at the remote client side, all data received on the remote receiver
connection (RX) will be internally loop-backed to the transmitter (TX)
connection.
Caution: Looping of Ethernet may cause a broadcast storm.
Remote Client Side
CH1 Loopback
Function Enabled
Local Client
SFP CH 1
1G
SFP CH 7
FRM
220
-TM
-10GM
u
x
10G
SFP+ LINE
FRM
220
-TM
-10GM
u
x
Remote Client
SFP CH 1
1G
SFP CH 7
Switch
Switch
Switch
Switch
Switch
Switch
Switch
Switch
Switch
Switch
Switch
Switch
Switch
Testing
Device
