363-206-295
Transmission and Synchronization Interfaces
5-14
Issue 1
December 1997
Figure 5-6a shows the CO system is internally timed (free-running). At the remote
terminal (RT), the TG derives its timing from the incoming optical signal and uses
it to time itself and loop timing back to the CO.
Figure 5-6b and Figure 5-6c show the CO timed from an external stratum 3 or
better source. The RT derives its timing from the incoming optical line and can
send a DS1 output to a BITS clock.
The external timing configuration (Figure 5-6d) uses external DS1 timing to each
DDM-2000 Multiplexer in the network. Since this configuration requires local office
clocks at each site, it is most suited to interoffice applications. A DDM-2000
network may have all DS1 references traceable to a primary reference source
(synchronous operation) or multiple primary reference sources (plesiochronous
operation).
The PRS is equipment that provides a timing signal whose long-term accuracy is
maintained at 10
-11
or better with verification to universal coordinated time (time
and frequency standard maintained by the U. S. National Institute of Standards
and Technology), and whose timing signal is used as the basis of reference for the
control of other clocks in a network.
An interoffice ring should have each node externally timed if BITS clocks are
available. All other rings should have one node externally timed (two in some dual
homing configurations) and the rest of the nodes line timed. See 363-206-200,
DDM-2000 Multiplexer Applications, Planning, and Ordering Guide, for more
synchronization information.
Table 5-2 summarizes the DDM-2000 OC-12 synchronization modes for the
current software release.
Table 5-2.
DDM-2000 OC-12 Multiplexer Synchronization
Application
Ring (R7.0)
Free-Running
X
Line-Timing
X
External Timing
X
DS1 Sync Output
X
Synchronization Messaging
X
Automatic Synchronization Reconfiguration
X
Содержание DDM-2000 OC-12
Страница 1: ...363 206 295 Issue 1 December 1997 DDM 2000 OC 12 Multiplexer Release 7 0 User Service Manual Volume I ...
Страница 37: ...Tables xxxviii Issue 1 December 1997 A A SONET Overview A 1 SONET Payloads A 18 A 2 SONET Transport Rates A 19 ...
Страница 506: ...INS PROG 8 of 8 Page INS PROG COMMANDS RELATED rtrv eqpt rtrv ne OC 12 DDM 2000 1997 December 1 Issue 11 89 ...
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Страница 565: ...RTRV OC3 3 of 3 Page RTRV OC3 COMMANDS RELATED rtrv sync 11 148 1997 December 1 Issue OC 12 DDM 2000 ...
Страница 664: ...SET FEAT 3 of 3 Page SET FEAT COMMANDS RELATED rtrv feat OC 12 DDM 2000 1997 December 1 Issue 11 247 ...
Страница 766: ... Ctl T TOGGLE 2 of 2 Page Ctl T TOGGLE COMMANDS RELATED logout rlgn OC 12 DDM 2000 1997 December 1 Issue 11 349 ...
Страница 847: ...Multiplexer OC 12 DDM 2000 7 Release TARP TOP Manual User Service II Volume 363 206 295 1 Issue 1997 December ...
Страница 867: ...363 206 295 TOP Maintenance and Operation BLANK LEFT INTENTIONALLY PAGE THIS 12 1997 December 1 Issue ...
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Страница 1565: ...363 206 295 DLP 543 6 of 5 Page 1997 December 1 Issue Network Broadcast Video of Test Transmission 2 Figure ...
Страница 1566: ...DLP 543 363 206 295 1997 December 1 Issue 6 of 6 Page Network Ring Virtual ATM of Test Transmission 3 Figure ...