Octal DS3/STS-1 I/O Front Module
Plexus 9000 Planning and Engineering Guide
Issue 4, March 26, 2004
Section 130-120-600
5-154
Telica,
Inc.
In the receive direction the serial data from the SF module is received at
the Serial In/Parallel Out interface to be converted to parallel data for the
FSU circuitry. The FSU converts the ATM cells back to a VT signal for
the DS-3 or STS-1 interface that multiplexes them back to DS-3 or STS-1
for the midplane and the rear module.
5.13.3.1
DS-3/STS-1 LIU and Super Mapper
Each module has eight line interface circuits. See
for the
Octal DS-3/STS-1 IOM block diagram illustration. The LBOs of the
DS3s are programmable using TL1 commands.
The Framer and Mapper circuitry demultiplexes each DS-3/STS-1 into
seven VT groups onto the TDM (Time-Division Multiplexed) bus to the
TSU. TDM signals received from the FSU are multiplexed back to a DS-3
or STS-1.
The DS3/STS-1 interface has programmable thresholds for loss of signal
(LOS), alarm indication signal (AIS), control slip seconds (CSS), coding
violations (CVs), errored seconds (ES) and severely errored seconds
(SES). The circuitry can also be configured to operate in M23 or C-bit
parity mode.
The DS3/STS-1 interface can loop individual DS3s or STS-1s for
diagnostic testing of line integrity. These loops can also be programmed
using TL1 commands.
5.13.3.2
To Switch Unit (TSU) and From Switch Unit (FSU) )
The TSU and FSU are circuit to ATM cell translators. The ATM output
of the TSU passes to the parallel/ serial interface that serializes the parallel
input to a 622 Mb/s signal for the SF module. The serial/parallel interface
accepts the 622 Mb/s signal from the SF module and converts it from
serial to parallel for the FSU.
5.13.3.3
Segmentation and Reassembly (SAR) )
There is a Segmentation and Reassembly (SAR) unit on the PCI bus of
each module for inter-module messaging. The SAR connects to the
TSU/FSU on the IOM to perform the conversion from/to cells. The TSU
has a small Virtual Channel Identifier (VCI) to ATM switch fabric port
look-up function to get frames from the IOMs to the SP.