363-206-305
Transmission and Synchronization
Issue 3 June 2000
5-17
The existence of automatic synchronization reconfiguration does not change the
system's behavior on traditional line failures; for example, loss of frame (LOF),
loss of pointer (LOP), loss of signal (LOS), and others.
Examples
5
In this section, some detailed examples are given to show specifically how the
synchronization messages propagate through the DDM-2000 FiberReach
network and assist in the recovery from a fiber failure. Through these examples,
one can extend the same concept to any other network that may include different
topologies, number of sites, failure locations, and number of BITS clocks.
Synchronization messaging using the SONET K2 byte and S1 byte can be
disabled on a per OC-N interface using the
set-ocn
command. (See Table 5-2.)
Zeros will be transmitted on bits 1-3 of the K2 byte if this is done; all ones will be
transmitted on bits 5-8 of the S1 byte if this is done. The timing and
synchronization status of a shelf can be determined using the
rtrv-sync
command.
Synchronization Reconfiguration in an Access
Ring
5
Figure 5-8a shows the access ring operating in its normal configuration. The
DDM-2000 Multiplexer at the central office (CO) is externally timed, and each of
Table 5-2. Synchronization Messages using S1 Byte
*
* This table is applicable when a 28-type or 29-type OLIU is in the Main
slot.
Received Message Active Timing Mode
â€
†This column applies only when provisioned for line timing mode.
Don't Use Holdover
Traceable SONET Clock OK to use
Traceable Stratum 3
‡
‡ Presently, DDM-2000 FiberReach Multiplexers cannot generate these
messages, but they could be transmitted and supported for auto-
reconfiguration if any of these are received by DDM-2000 FiberReach
Multiplexer.
OK to use
Traceable Stratum 2
‡
OK to use
Sync Trace Unknown OK to use
PRS Traceable
‡
OK to use
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