System Architecture - Optelecom 9522A Installation And Operation Manual

System Architecture

The Model 9522A can be configured into three basic network architectures with almost unlimited variations.
Variations include unlimited branches from the main trunks. Typically the rack-mountable Model 9522A or
9522AY are used at a central hub. Standalone Models 9526AY and 9526A are used at the remote (local)
locations. However either modem can be used in either installation if so desired.
N A
ETWORK RCHITECTURE
The three basic network architectures are:
 Daisy Chain with One Master Controller
 Daisy Chain with Two Master Controllers
 Fault Tolerant Counter Rotating Ring
The following sections describe the Operating Modes and are they are used to build the different network
types.
O M
PERATING ODES
The modems must be configured into one of four operating modes depending on the network type being
utilized. The different modes and the networks they support are characterized by the internal signal routing
within the modem among the primary and secondary data I/O ports and the two optical transmitter/ receiver
ports.
To set up a modem into one of the four operating modes, the user selects one of four UP/DOWN combinations
for switches 1 and 2 of S1. These four modes are characterized by the specific signal routing within the
modem and the availability of the various operational features such as the expansion port, anti-streaming,
fiber activity CTS inhibit, and ring break detection. Figure 4 shows the signal routing within the modem. The
following sections include a detailed description of each mode.
Master Daisy Chain (MDC) Mode
In this mode the Primary data port is configured as a Master port and the Secondary port is configured as a
Local port. Data input to the Primary data port (TD) is transmitted out via the optical ports and output from
the Secondary data port (RD). Data input to the Secondary data port (TDE) will be output from the Primary
port (RD), but will not enter the optical network. Conversely, optical data input via the TX2/RX2 optical port or
data input via the Secondary port (TDE) will be output via the Primary port (RD). In this mode, priority select
is not used. This mode is normally used in a network with numerous modems in local daisy chain mode where
the master is located at the head of a daisy chain trunk. In this mode neither Optical nor Electrical side anti-
streaming may be employed.
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