13 — System timing and timing sources
13-6
2902 MainStreet Technical Practices
90-2906-01 May
2002
Enabling a timing source
When a source is enabled, it becomes available to the system as a source of timing.
If an enabled source has a higher preference (lower class number) than the current
source of timing, the enabled source is automatically selected as the new source of
timing.
When a source is disabled, it becomes unavailable to the node as a source.
A timing source must be disabled before its configuration can be changed.
Selecting a timing source
When you select a timing source, it becomes the current source regardless of its class
number. Its status changes from Ready to Current.
When you deselect a source, its status changes from Current to Ready. The system
will then automatically select the Ready source with the highest preference (lowest
class number) to be the new current source.
Procedure 13-4 To enable and select a source
where
source number
is 1 or 2
13.3
Types of synchronization
Each timing source can be set for the following type of synchronization:
•
internal (FREE_RUN)
•
derived (DERIVED)
If the current timing source is lost or becomes degraded or if the SSU cannot
synchronize to it, the system automatically switches to the other source, providing it
has been configured and is available. If this source fails and the first source is still
unavailable, the system switches to its internal clock (free run).
ENABLE/DISABLE
SELECT/DESELECT
CONFIG — SYNCH — SRC_NUMBER — <
source number
>
↵
SK000474
Note —
Free-run mode should be used only as a last resort because
the node is not fully synchronized with the network in this mode.
Summary of Contents for MainStreet 2902
Page 1: ...2902 MainStreet Network Termination Unit Release 1 0 H T E C H N I C A L P R A C T I C E S ...
Page 40: ...3 Mounting the unit 3 8 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
Page 50: ...4 Ground and power connections 4 10 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
Page 68: ...6 Connecting to the network 6 4 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
Page 90: ...7 Connecting to data devices 7 22 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
Page 108: ...10 Node management 10 10 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
Page 150: ...14 CPSS 14 6 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
Page 218: ...20 Codirectional DCM 20 6 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
Page 234: ...22 HCM rate adaption 22 10 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
Page 246: ...23 Cross connecting circuits 23 12 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
Page 254: ...24 Visual indicators 24 8 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
Page 266: ...25 Alarms 25 12 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
Page 278: ...26 System diagnostics 26 12 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
Page 298: ...27 Loopbacks 27 20 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
Page 332: ...Glossary GL 8 2902 MainStreet Technical Practices 90 2906 01 May 2002 ...
Page 343: ......
Page 344: ... 2002 Alcatel All rights reserved 90 2906 01 95 1820 01 00 C ...