SONET/SDH Automatic Protection Switching Software

APS technology (Automatic Protection Switching) is one of the major benefits of SONET (Synchronous Optical Network) as well as SDH (Synchronous Digital Hierarchy). SONET/SDH APS is well defined by standards in contrast to T and E carrier technologies where proprietary schemes are employed. NComm's APS software in the NComm TMS® family of telecom source code provides the necessary functionality to monitor each line as well as the control/switching over multiple lines. The Linear APS technology can be implemented in both the 1+1, 1:1 and 1:n architectures. In addition to Linear APS, the ring APS model Unidirectional Path Switched Ring (UPSR) can be used.  Future APS releases wwill support Unidirectional Line Switched Ring (ULSR), Bidirectional Line Switched Ring (BLSR), and Bidirectional Path Switched Ring (BPSR) APS technology.


Target APS Software Applications

  • Self-Healing protection functionality such as that found in SHNS (Self-Healing Network Service) and AccuRing
  • SONET/SDH Multiplexers
  • Class 5/4 Switches

APS Software Main Features

  • Full implementation of linear APS state machine
  • Designed to accommodate multiprocessor arrangements
  • Works across various hardware architectures
  • Built-in Wait-to-Restore feature
  • Models fully compliant with GR-253-CORE
  • SONET/SDH framer device independent
The NComm APS software implements controller and monitor blocks resulting in a totally flexible APS solution. It includes a fully implemented Linear and UPSR APS state machine(s). The modules have built-in bridge and selection control.  Linear APS includes complete transmission and acceptance of K1, K2 bytes. 1+1, 1:1 and 1:n (n = 1 to 14) systems are easy to build and can be run time configurable. In conjunction with the SONET/SDH TMS software, Signal Fail and Signal Degrade with configurable hold-off times provide the foundation of the
APS switch triggers.
Wait-to-Restore (WTR) timers are also configurable with proper overrides for subsequent Signal Fail/Degrade indications. Switch request priorities are fully operational as well as equal priority mediation. All switch commands are accessible including Clear, Lockout of Protection, Forced Switch of Working, Forced Switch of Protection, Manual Switch of Working and Manual Switch of Protection. The Exercise command is also supported. Control commands include Lockout of a Working Channel and Clear.

APS Technology and Software Architecture

APS Software for Linear APS Technology


Download the Linear APS for SONET/SDH TMS datasheet

Download the Unidirectional Path Switch Ring APS for SONET/SDH TMS datasheet

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