The OC-3/12/48/192 high-speed circuit packs (as well as LNW80) contain an embedded Stratum 3 timing generator. This timing generator is used when the Alcatel-Lucent 1665 DMX is configured in a free running mode.
Line timing and external timing are also supported by Alcatel-Lucent 1665 DMX. Line timing is derived from an incoming MAIN or tributary OC-3/12/48/192 line, while external timing is derived from an external timing source. Line timing from tributary optical interfaces is supported. The timing generator also provides a BITS clock output derived from the incoming line signal.
Alcatel-Lucent 1665 DMX can generate a DS1 timing output to time other externally-timed systems. The DS1 output is derived from a line reference. Alcatel-Lucent 1665 DMX also supports E1 timing output when equipped with a VLF Main circuit pack.
Important!
When the Alcatel-Lucent 1665 DMX is provisioned for SONETSYNC, both input ext timing reference and ext reference output are DS1. When the Alcatel-Lucent 1665 DMX is provisioned for SDHSYNC, both input ext timing reference and ext reference output are E1.
Alcatel-Lucent 1665 DMX uses Synchronization Status Messages (SSMs), transported in the S1 byte of the SONET or SDH overhead. To pass timing status information to different nodes in an access transport network, Alcatel-Lucent 1665 DMX also supports SSMs in the DS1 or E1 external timing reference inputs and outputs. They contain clock quality labels that allow the NE to select the most suitable synchronization reference from the set of available references. The purpose of the SSMs is to allow the NEs to reconfigure their synchronization references autonomously while avoiding the creation of timing loops.
Alcatel-Lucent 1665 DMX can derive timing references from any SONET/SDH optical line entering Main, Function Unit, or Growth slots.
All optical circuit packs, except the LNW705 and LNW785, can derive a 6.48 MHz timing signal from an incoming optical line.
Network Time Protocol (NTP) assures accurate synchronization of the Alcatel-Lucent 1665 DMX with reference to radio and/or atomic clocks located on the Internet.
| November 2011 | Copyright © 2011 Alcatel-Lucent. All rights reserved. |