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Self-healing ring:
This configuration is the most complex one and highlights the various features of
the PX-2300 modems. In such a network configuration, data is transmitted down both rings (one
clockwise and the other counter-clockwise). In addition to the user’s data, PX-2300 network and
diagnostic commands are transmitted on the fibers. These signals are used to monitor the integrity of the
fiber network and perform the necessary diagnostics and fail-safe network reconfiguration to ensure the
fail-safe operation of the PX-2300 network. The PX-2300 also supports dual master modems for even
greater protection and redundancy.
Figure 2-2 below illustrates how the PX-2300 modems can be configured in a SHR network. The head-
end computer or controller is connected to the modem configured as the master modem. Data from this
master is then transmitted in both directions around the ring and dropped off at each of the remote or
slave locations.
Since the customer’s data is asynchronous, and not guaranteed to be present at all times, Meridian uses
its proprietary network control/diagnostic signals to continuously monitor the network’s integrity in both
directions and provide network performance and fault location information back to the system controller.
The default transmit/receive direction for the data network’s data is in the clockwise direction (‘A’ ring). In
the event of a fiber break or modem failure, the modems automatically switch to the back up or counter-
clockwise rotating ‘B’ ring to detect the network’s data. Other SHR networks provide a simple local
contact closure to indicate or alarm that the network has failed or gone into the self-healing mode of
operation. Meridian’s PX2300 modems provide this same local contact closure for compatibility but also,
through the
SpectraSmart
network management system, provide both local and remote indication and
identification of the fault – a major technology breakthrough and significant cost advantage to network
management.
Figure 2-1
Multidrop String Configuration
Summary of Contents for 2300M Series
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