Circuit Pack Descriptions
7-92 Issue 8.0 July 2002
Control Circuitry 7
The board controller circuit controls most circuit pack activities. The board
controller circuit interfaces with the Line Controller (LNCTL) circuit pack via the
board controller local area network (BCLAN).
The OC48 RCVR A/D circuit pack reports the status of the circuit pack and the
incoming OC-48 signal, as well as inventory information (CLEI code, serial
number, etc.). The status information is used by the LNCTL circuit pack for fault
detection and isolation. Conversely, the OC48 RCVR A/D circuit pack responds to
control signals from the LNCTL circuit pack.
The OC48 RCVR A/D circuit pack also accesses the SONET transport overhead
bytes and routes them via the transport overhead channel interface to the optional
OHCTL (TERM) circuit pack.
Timing Circuitry 7
The receive byte processor of the OC48 RCVR A/D circuit pack generates a
25.92 MHz reference signal from the 2.5 GHz clock signal and sends it to the TG3
(DS1) circuit packs.
Protection Circuitry 7
High Speed Protection. 7In bidirectional ring applications, the FT-2000 OC-48
Add/Drop-Rings Terminal performs revertive bidirectional 2-fiber ring protection
switching. The OC48 RCVR A/D circuit pack is protection switched by the LNCTL
circuit pack in response to an external command, incoming signal failure, or
internal equipment fault.
The switch matrix on the protection OC48 RCVR A/D circuit pack also allows
access to the protection OC-48 high speed line (OC-48 point-to-point
applications) or the protection 155.52 Mb/s signals (STS-3 tributaries in
bidirectional 2-fiber ring applications) for low priority traffic or for restoration
purposes.
Low Speed Protection. 7Low speed protection switching in the receive direction is
done by routing the 155.52 Mb/s signal for the failed service electrical low speed
interface circuit pack (DS3 or STS1E) to the protection DS3 or STS1E circuit
pack. The OC48 RCVR A/D circuit pack also bridges the same 155.52 Mb/s signal
(STS-3/3c) to the active and standby OC3 (1.3 STD) circuit packs. Low speed
protection switching is performed in response to commands from the LNCTL
circuit pack via the BCLAN.
Dual Ring Interworking Protection. 7The OC48 RCVR A/D circuit pack at the
primary node of a dual ring interworking application bridges the 155.52 Mb/s
signal (STS-3 tributary) in the drop direction to provide two identical signals to the
other ring. One 155.52 Mb/s signal is sent to the local low speed interface circuit
pack and the other 155.52 Mb/s signal is sent to the OC48 TRMTR circuit pack in
the opposite direction for transmission to the secondary node. In Release 7 and
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