363-206-295
Transmission and Synchronization Interfaces
Issue 1 December 1997 5-31
With OC-N timing distribution, the OC-N line signal, rather than a DS1 multiplexed
into the SONET payload, will provide a timing transport mechanism better suited
to a complex, heavily interconnected SONET network. In this configuration, a DS1
reference from the CO BITS clock still times the OC-N transmitted to the remote
site; at the remote site, a DS1 output reference is created directly from the
received OC-N signal (Figure 5-11).
The stratum level of the BITS clock at the CO must be equal to or better (more
accurate) than the stratum level of the BITS clocks used at the other RT sites. This
is necessary to maintain the stratum level hierarchy.
Figure 5-11. OC-N Derived DS1 Timing Reference
DDM-2000
Other
Network
Elements
DS1
DS1 out
DS1
External Clock
(Stratum 3 or better)
DDM-2000
RT
CO
Bits Clock
PRS
Traceable
Source
DS3/OC-3/DS1/EC-1 DS1/EC-1/DS3/OC-3
OC-N
tpa 849847/01
TG
TG
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