363-206-295
Transmission and Synchronization Interfaces
Issue 1
December 1997
5-17
DS1 Timing Output Integrity
5
The DS1 timing outputs are typically used to distribute timing from the BITS clock
in one office (master) to the BITS clock in the next office (slave), using the SONET
transmission facilities between them as the synchronization vehicle. The BITS are
typically of stratum 2 or stratum 3 accuracy. The DDM-2000 Multiplexer does not
introduce its own internal timing source onto the SONET facility but merely
transfers the quality of its timing reference. This ability preserves the required
hierarchical structure of the timing network and should be maintained at all times.
If the DDM-2000 Multiplexer at the master office enters holdover due to a
disconnected reference cable or a local BITS failure, the quality of the DS1 timing
output at the slave office will now be traceable directly to the DDM-2000
Multiplexer. If the master DDM-2000 system contains a TG3 circuit pack, stratum
3 accuracy will be maintained indefinitely. This provides acceptable timing for
stratum 3 NEs at slave offices. If the master DDM-2000 contains a TGS circuit
pack, stratum 3 accuracy will be maintained for the first 24 hours of holdover. After
the first 24 hours, the DDM-2000 system could exceed stratum 3 accuracy.
If a DDM-2000 system contains a TGS pack, it may change the output of its
derived DS1 under some conditions. If the incoming synchronization message is
better than internal clock (IC) the derived DS1 will be an ‘all ones’ with framing.
This format is suitable for providing synchronization to a BITS of stratum 3
accuracy. If the co-located DDM-2000 enters holdover or the incoming
synchronization message is IC or worse, the derived DS1 format will change to ‘all
ones’ without framing (AIS). This will prevent a BITS from using this input and
force the BITS to either select a new input or enter holdover. This change to AIS
preserves the stratum timing hierarchy by allowing the BITS to synchronize from a
clock of equal or higher quality.
Available in R5.1 and later is the threshold AIS feature. This feature allows the
user to select the value of the incoming message that causes the derived DS1
output to output AIS. This feature will allow stratum 2 BITS clock to receive timing
from a TGS or TG3 without violating stratum timing rules.
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 ...
Страница 528: ...RTRV ATTR ALM 2 of 2 Page RTRV ATTR ALM COMMANDS RELATED set attr alm OC 12 DDM 2000 1997 December 1 Issue 11 111 ...
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 ...
Страница 1145: ...Order Circuit 363 206 295 NTP 029 1 of 1 Page 1997 December 1 Issue Unused LISTED ORDER IN BELOW ITEMS DO TO GO DETAILS FOR ...
Страница 1146: ...Order Circuit 363 206 295 NTP 030 1 of 1 Page 1997 December 1 Issue Unused LISTED ORDER IN BELOW ITEMS DO TO GO DETAILS FOR ...
Страница 1182: ...Turnup System 363 206 295 NTP 033 1 of 1 Page 1997 December 1 Issue Unused LISTED ORDER IN BELOW ITEMS DO TO GO DETAILS FOR ...
Страница 1243: ...Clearing Trouble 363 206 295 TAP 107 1 of 1 Page 1997 December 1 Issue Unused ...
Страница 1393: ...363 206 295 DLP 513 1 of 1 Page 1997 December 1 Issue Unused ...
Страница 1394: ...363 206 295 DLP 514 1 of 1 Page 1997 December 1 Issue Unused ...
Страница 1456: ...363 206 295 DLP 523 7 of 7 Page 1997 December 1 Issue OC 12 via Access Broadcast Video for Cross connections of Example 4 Figure ...
Страница 1465: ...DLP 525 363 206 295 1997 December 1 Issue 6 of 2 Page Schematic Ring Virtual ATM Sample 1 Figure ...
Страница 1469: ...DLP 525 363 206 295 1997 December 1 Issue 6 of 6 Page Ring Virtual ATM OC 12 DDM 2000 for Cross connections of Example 4 Figure ...
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 ...