DS3172 Maxim Integrated, DS3172 Datasheet - Page 94

• Manufacturer Part Number: DS3172
• Description: Network Controller & Processor ICs Dual DS3/E3 Single Chip Transceiver
• Manufacturer: Maxim Integrated

Specifications of DS3172

• Part # Aliases: 90-31720-000

DS3171/DS3172/DS3173/DS3174
A Loss Of Frame (LOF) condition is declared by the LOF integration counter when it has been active for a total of T
ms. The LOF integration counter is active (increments count) when an OOF condition is present, it is inactive (holds
count) when an OOF condition is absent, and it is reset when an OOF condition is absent for T continuous ms. T is
programmable (0, 1, 2, or 3). An LOF condition is terminated when an OOF condition is absent for T continuous
ms.
A Change Of Frame Alignment (COFA) is declared when the G.832 E3 framer updates the data path frame
counters with a frame alignment that is different from the current data path frame alignment.
A Loss Of Signal (LOS) condition is declared when the HDB3 encoder is active, and it declares an LOS condition.
An LOS condition is terminated when the HDB3 encoder is inactive, or it terminates an LOS condition.
An Alarm Indication Signal (AIS) condition is declared when 7 or less zeros are detected in each of two consecutive
frame periods that do not contain a frame alignment word. An AIS condition is terminated when 8 or more zeros are
detected in each of two consecutive frame periods.
A Receive Unframed All 1’s (RUA1) condition is declared if in each of 4 consecutive 2047 bit windows, five or less
zeros are detected and an OOF condition is continuously present. A RUA1 condition is terminated if in each of 4
consecutive 2047 bit windows, six or more zeros are detected or an OOF condition is continuously absent.
A Remote Defect Indication (RDI) condition is declared when four consecutive frames are received with the RDI bit
(first bit of MA byte) set to one. An RDI condition is terminated when four consecutive frames are received with the
RDI bit set to zero.
Three types of errors are accumulated, framing, parity, and Remote Error Indication (REI) errors. Framing errors
are determined by comparing FA1 and FA2 to their expected values. The type of framing errors accumulated is
programmable (OOFs, bit, byte, or word). An OOF error increments the count whenever an OOF condition is first
detected. A bit error increments the count once for each bit in FA1 and each bit in FA2 that does not match its
expected value (up to 16 per frame). A byte error increments the count once for each FA byte (FA1 or FA2) that
does not match its expected value (up to 2 per frame). A word error increments the count once for each FA word
(both FA1 and FA2) that does not match its expected value (up to 1 per frame).
Parity errors are determined by calculating the BIP-8 (8-Bit Interleaved Parity) of the current E3 frame (overhead
and payload bytes), and comparing the calculated BIP-8 to the EM byte in the next frame. The type of parity errors
accumulated is programmable (bit or block). A bit error increments the count once for each bit in the EM byte that
does not match the corresponding bit in the calculated BIP-8 (up to 8 per frame). A block error increments the
count if any bit in the EM byte does not match the corresponding bit in the calculated BIP-8 (up to 1 per frame).
REI errors are determined by the REI bit (second bit of MA byte). A one indicates an error and a zero indicates no
errors.
The receive alarm indication (RAI) signal is high when one or more of the indicated alarm conditions is present, and
low when all of the indicated alarm conditions are absent. Setting the receive alarm indication on LOS, OOF, LOF,
or AIS is individually programmable (on or off).
The receive error indication (REI) signal will transition from low to high once for each frame in which a parity error is
detected.
10.6.8.9 Receive G.832 E3 Overhead Extraction
Overhead extraction extracts all of the E3 overhead bytes from the G.832 E3 frame. All of the E3 overhead bytes
FA1, FA2, EM, TR, MA, NR, and GC are output on the receive overhead interface (ROH, ROHSOF, and
ROHCLK).
The EM byte is output as an error indication (modulo 2 addition of the calculated BIP-8 and the EM byte.
The TR byte is sent to the receive trail trace controller.
The payload type (third, fourth, and fifth bits of the MA byte) is integrated and stored in a register with change and
unstable indications. The integrated received payload type is also compared against an expected payload type. If
the received and expected payload types do not match (See
Table
10-30), a mismatch indication is set.
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