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LTPS-UM-8013-03 Front-Panel Description
D3LX CO and RMT Modules August 30, 2002 5
Automatic Switching
The 1:1 (Line) Protect mode transmits identical traffic across two parallel systems. The working and protect D3LX
modules provide Automatic Protection Switching (APS) compatible with the remote D3LX module. APS is
non-revertive and bidirectional and may be forced or disabled through the front-panel pushbuttons or the SCU
software.
Service is automatically switched from the online D3LX module to the offline module when one or more of the
following events occur:
• Offline module detects a failure in the online module.
• Online module detects an optical failure. (LOS, LOF, or BER threshold is exceeded.)
APS is completed within 50 msec of the initiation of a switch. After the occurrence of three automatic switches
within a 24-hour period, APS is locked out. APS may be enabled again through the front panel interface or the
craft interface.
APS to the offline module can be disabled. To do this, simultaneously press the LMPTST/APS and ENABLE
pushbuttons on the online module’s front panel. APS can be restored by pressing both pushbuttons a second time.
BER Monitoring
The optical link is continuously monitored for bit errors. If the bit errors exceed a predetermined threshold, and
the D3LX is configured for protection, protection switching occurs and an alarm is indicated. The optical alarm
is indicated when the threshold exceeds 10
-6
to 10
-10
(default is 10
-8
). The optical switch threshold may be set
between 10
-4
and 10
-10
(default is 10
-6
).
Manual Switching
Service can be manually switched from the online D3LX module to the offline module by simultaneously pressing
the LMPTST/APS and ENABLE pushbuttons located on the offline module’s front panel. This disables the APS
causing the APS LED to turn yellow. The ONLINE LED of the new online module (formerly the protect module)
turns green, indicating a successful transfer of service. The ONLINE LED of the new offline module (formerly
the working module) is not lit, indicating it is in standby mode and not carrying the DS3 service.
APPLICATIONS
D3LX modules can be used in a number of solutions:
• Switched Multimegabit Data Service (SMDS) Applications—D3LX modules support the transmission of
SMDS service through the network.
• Private Line Interconnect Applications—D3LX modules provide private point-to-point LAN interconnect
services through the use of the D3LX.
• DS3 Video Distance Learning Applications—D3LX modules provide high quality video signal transmission
that is the most cost-effective solution for DS3 video transport.
• DS3 Asynchronous Transport Mode (ATM) Applications—D3LX modules provide high speed ATM
services using D3LX at a fraction of the cost of an OC-3 multiplexer.