GSM1010M Gigabit Converter
13
11 - LST
( Link Segmentation Test )
The LST in the GSM1010M is used to notify one Network Device upon a link failure in the
other Network Device, or in the opposite direction (Fault Propagation).
The setting of the LST commands has absolutely no affect as long as no link failure is
detected. Thus, data is communicated normally.
The LST commands have two positions per data link direction ((FO>>TP, TP>>FO)
The LST command TP>>FO controls LST signals from the TP port to the Fiber port.
When this LST command is preset to LST OFF, a link down at the TP port switches off
the Fiber output port, thus, signaling the other device upon the failure. When the
command is preset to LST ON, a link down at the TP port generates an idle signal that is
transmitted at the fiber output port, which does not affect the other attached device,
but will cause the Link LED to light. (provided that the link is intact and functional)
The LST command FO>>TP controls the LST signals from the Fiber port to the TP port.
When this command is set to LST Off, a link down at the Fiber port switches off the TP
output port, thus, signaling the attached device upon the failure. When the command is
set to LST ON, a link down at the Fiber port generates an idle signal that is transmitted at
the TP output port, which does not affect the attached device, but the link LED of which
will lit (provided that the link is intact and functional)
When switching to LST ON (Test mode) the appropriate LST LED will light accordingly.
Default Operation Mode: LST ON (“TEST” mode)
Users that do not require real time alert (Fault Propagation) upon a failure from one
Network Device to the other Network Device should set both the LST commands of both
converters to LST ON mode of operation via the management.
Users requiring real time alert (Fault Propagation) upon a failure may define one direction
of alert, or both directions. This can be from Network Device B to Network Device A
or/and
the other way. In this case the LST commands are set to LST OFF mode.
LST Operation
Figure –1 shows a typical installation when Fault Propagation (LST OFF) from Network
device B to Network Device A is selected.
Figure – 1 LST OFF operation (Link failure notification)
