
XRT7245
DS3 UNI FOR ATM
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PRELIMINARY
REV. 1.03
4
The UNI provides 54 bytes of on-chip RAM that
allows for the generation and transmission of “user-
specified” OAM cells. The Transmit Cell Processor
will generate and transmit these OAM cells upon
software command.
The Transmit Cell Processor will (optionally) scramble
the Cell Payload bytes and (optionally) compute
and insert the HEC (Header Error Check) byte.
This HEC byte will be inserted into the fifth octet of
each cell prior to being transferred to the Transmit
PLCP Processor (or the Transmit DS3 Framer).
The Transmit PLCP Processor will pack 12 ATM cells
into each PLCP frame and automatically determine
the nibble-stuffing option of the current PLCP frame.
These PLCP frames will also include an overhead
byte that reflect BIP-8 (Bit Interleaved Parity) calcu-
lation results, a byte that reflects the current stuffing
option status of the current PLCP frame, Path
Overhead and Identifier bytes, and diagnostic-
related bytes reflecting any detected BIP-8 errors
and alarm conditions detected in the Receive section
of the UNI chip.
These PLCP frames (or “Direct Mapped” ATM
cells) will be inserted into the payload of an outgo-
ing DS3 frame, for transmission to the “Far-End” Ter-
minal, by the Transmit DS3 Framer. The Transmit
DS3 Framer will transmit FEAC (Far End Alarm &
Control) messages to the Far-End Receiver via an
on-chip FEAC Transceiver.Additionally, the Trans-
mit DS3 Framer can transmit path maintenance
data link messages to the Far-End Terminal via the
on-chip LAPD Transmitter.
Note:
The Transmit DS3 Framer will support either M13 or
C-bit Parity Framing Formats.
THE MICROPROCESSOR INTERFACE SECTION
The Microprocessor Interface Section allows a user (or
a local “housekeeping” processor) to do the following:
To configure the UNI IC into a wide variety of oper-
ating modes; by writing data into any one of a large
number of “read/write” registers.
To monitor many aspects of the UNI’s performance
by reading data from any one of a large number of
“read/write” and “read-only” registers.
To run in a “polling” or “interrupt-driven” environment.
The UNI IC contains an extensive interrupt structure
consisting of a wide range of interrupt enable and
interrupt status registers.
To command the UNI IC to transmit OAM cells,
FEAC messages and/or LAPD Messages frames,
upon software command.
To read in and process received OAM cells, FEAC
messages and/or Path Maintenance Data Link
Messages from the UNI IC.
The Microprocessor Interface allows the user to
interface the XRT7245 DS3 UNI to either an Intel
type or Motorola type processor. Additionally, the
Microprocessor Interface can be configured to
operate over an 8-bit or 16-bit data bus.
The Microprocessor Interface section includes a
“Loss of Clock Signal” protection feature that auto-
matically completes (or terminates) a “Read/Write”
operation, should a “Loss of Clock Signal” event
occur.
PERFORMANCE MONITOR SECTION
The Performance Monitor Section of the XRT7245
DS3 UNI consists of a large number of “Reset-upon-
Read” and “Read-Only” registers that contains cumu-
lative and “one-second” statistics that reflect the per-
formance/health of the UNI chip/system. These cu-
mulative and “one-second” statistics are kept on
some of the following parameters.
Number of Line Code Violation events detected by
the Receive DS3 Framer
Number of Framing Bit (F- and M-bit) errors
detected by the Receive DS3 Framer
Number of P-bit Errors detected by the Receive
DS3 Framer
Number of FEBE Events detected by the Receive
DS3 Framer
Cumulative number of BIP-8 errors, detected by
the Receive PLCP Processor
Number of PLCP framing errors, detected by the
Receive PLCP Processor
Cumulative sum of the FEBE value, in the incoming
G1 bytes (within each PLCP frame), received by
the Receive PLCP Processor
Number of Single-bit HEC byte Errors detected
Number of Multi-bit HEC byte Errors detected
Number of Received Idle Cells
Number of Received Valid (User and OAM) cells
discarded
Number of Discarded Cells
Number of Transmitted Idle Cells
Number of Transmitted Valid Cells
TEST AND DIAGNOSTIC SECTION
The Test and Diagnostic Section allows the user to
perform a series of tests in order to verify proper
functionality of the UNI chip and/or the user’s system.