cx29600 Mindspeed Technologies, cx29600 Datasheet - Page 68

• Manufacturer Part Number: cx29600
• Description: Optiphytm - M155 Sts-3 Sonet/sdh Multiplexer
• Manufacturer: Mindspeed Technologies

2.0 Functional Description
2.4 SONET/SDH Framer and Overhead Processor
2.4.2 Section Overhead
Table 2-13. Section Overhead Transmit and Receive Functions
2-24
2.4.2.1 A1, A2 Severely
2.4.2.2 Loss of Frame
Errored Frames (SEF)
The Section Overhead handles the transport of the STS/STM frame across the
physical medium and section-level communications. Its functions are framing
and scrambling on the transmit side, and section error monitoring on the receive
side. The transmit and receive functions of the Section Overhead bytes are shown
in
NOTE:
In normal operation, the A1 and A2 bytes contain F6h and 28h respectively, and
are used by the CX29600 to determine the location of a frame within a data
stream.
conditions. SEF is declared if errors are detected in four consecutive frames. A
SEF condition causes the SEF bit in the RXSEC register to be set high and the
SEFCNT register to be incremented.
for A1 and A2 to 00 and 00 by setting the DisA1A2 bit high in the TXSEC
register. To insert a single framing error on the transmit side, software set the
InsFrErr bit in the ERRINS register high. This inverts the last A1 octet.
If the CX29600 detects 24 consecutive SEF, it will assert LOF bit (Loss of
Frame) in the RXSEC register. LOF is deasserted after eight frames of SEF
inactive.
A1/A2
B1
E1
F1
D1, D2, D3
J0
Z0
Table
The STS-3/STM-1 framing bytes, A1 and A2, are monitored for SEF
On the transmit side, A1 and A2 contain F6h and 28h by default. Software can
Byte
Undefined overhead positions carry 00h.
2-13.
Mindspeed Technologies
00 hex or external serial access External serial access
F6/28 hex, A1 inverted, or 00
Calculated, error insertion
option
From external pin
From TXF1 register
01 hex or 64-byte trace buffer
02, 03 hex
Transmit
™
Monitor out of frame state machine
Checked, errors counted
To external pin
To RXF1 register
Monitor Rx trace buffer, interrupt on
change
Not checked
Receive
CX29600 Data Sheet
29600-DSH-001-B
CX29600