NEC UPD98413 User Manual page 57

(4) Drop function of received OH byte
The µ PD98413 offers the following four means of obtaining the contents of the OH byte in a received frame.
• Drop register
• OH extract interface
• Section and Line DCC extract interface
• Reception of J0/J1 byte trace message
These means are used on the assumption that frame synchronization is established and that reception can be
performed normally.
(a) OH drop register
The µ PD98413 has drop registers that store the received contents of the following byte areas of the received
overhead. The CPU can check the received contents by reading each of these registers via the
management interface. For details of the drop registers, see Section 3.5 .
•
OH bytes having drop register
TOH: K1, K2, E1, E2, F1, D1 through D3, D4 through D12, J0, S1, 1st Z2
POH: J1, C2, F2, G1, H4, Z3, Z4, Z5
(b) OH extract interface
The µ PD98413 has an OH output interface through which a peripheral device can obtain the contents of the
OH byte of the received TOH and POH as signals. For details, see Section 4.4 .
(c) Section and Line DCC extract interface
The µ PD98413 has an output interface through which a peripheral device can obtain the contents of the
Section and Line DCC as signals. D1 through D3 bytes can be extracted via the Section DCC extract
interface, and D4 through D12 bytes can be extracted via the Line DCC extract interface, see Section 4.4.
(d) Reception of J0 and J1 trace messages
The µ PD98413 stores a 16- or 64-byte trace message in the J0 byte of the SOH or J1 byte of POH, to a
dedicated buffer and then reports it to the CPU. If the µ PD98413 is instructed to receive a message after the
message size and synchronization pattern (start or end pattern of the message) have been specified, it
stores a new message when it has detected it from the J0 (J1) byte string of a received OH, and reports this
message to the CPU by issuing an interrupt.
For details of the trace message reception function, see Section 3.6.2 .
(5) Detection of line failure
A function for reporting the events that monitor and detect receive data, such as line failures, alarms, and the
degradation of line quality, to the host via registers as OAM (Operation, Administration and Maintenance)
information is provided.
•
Detection of failure and alarm
•
Detection of cause of line quality degradation
•
Performance monitoring counter
•
Monitoring bit error rate
For details, see Section 3.4 .
CHAPTER 3 FUNCTIONAL OUTLINE
PRELIMINARY
NEC confidential and Proprietary
57