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PacketStar
®
PSAX 2300 Multiservice Media Gateway User Guide
, Issue 1
Release 9.0.0
Chapter 2 Hardware Description
Functional Description
modules reside below the cable turndown loops and air filter compartment in
the middle of the chassis. The rear panel provides power and ground termi-
nations for the chassis and additional module slots for future enhancements.
The chassis includes a midplane printed circuit board (PCB) designed to pro-
vide an interface between the front and rear panel slots. This design supports
N:1 protection for DS3, E3, and STS-1e modules while continuing to support
over 30 legacy PSAX I/O and server modules.
The Power Supply and Stratum modules operate in a load-sharing mode,
whereas the CPUn modules operate in an active/standby mode. All modules
are hot swappable.
Backplane
The chassis backplane distributes data, clock signals, and power to the mod-
ules. The backplane is based entirely on switching ATM cells. The backplane
has three segments; each segment has two buses, Bus A and Bus B. The
three-segment architecture of the backplane provides several layers of pro-
tection for system resources and functionality. In conjunction with the Stra-
tum 3–4 modules, this architecture provides the basic ATM concentration
technologies of the PSAX 2300 system. The design provides a maximum 3.9
Gbps total bandwidth and allows live (power supplied) insertion of primary
and redundant common equipment modules, and input/output and server
modules.
Power Supply Modules
Two -48 V dc Power Supply modules (see Figure 2-2) converts -48 V dc
power to voltages required by the chassis for normal operation and distrib-
utes power through the midplane to all of the modules in the chassis. The
modules are installed side-by-side below the cable turndown loops and air
filter compartment. Each module includes a variable-speed fan for power
supply and module cooling, status indicators, power connection to distribute
power to the midplane, and inline circuit protection. Facility power and
frame ground are connected to the chassis through the rear-panel connec-
tions.
The modules operate in a load-sharing mode to increase system reliability.
This configuration ensures that as long as one Power Supply module is active,
the entire system is fully powered. Under normal operation, each module
operates at one-half of its capacity. If one Power Supply module fails, the
other module takes over completely.
The variable-speed fans are controlled through the Stratum modules. The
Stratum modules sense the chassis temperature and change the fan speed to
maintain air flow and temperature through the chassis. The fan speed also
increases when the other fan stops operating due to failure or removal.
Circuit protection is provided through two fuses (one for the -48 V dc side
and one for the return side) located on the faceplate of the module.
Three LED indicators on the faceplate indicate the operational state of the
module.
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