PMC-Sierra PM5349 manual SPE Timing, Error Monitor

PMC-Sierra, Inc.

S/UNI-QUAD

DATASHEET

PM5349 S/UNI-QUAD

PMC-971239 ISSUE 6 SATURN USER NETWORK INTERFACE (155-QUAD)

optionally returned to the source node by signaling the corresponding Transmit Path Overhead Processor in the local SONET/SDH equipment to insert a path RDI indication.

Invalid pointer indications (inv_point), invalid NDF codes, new pointer indications (new_point), discontinuous change of pointer alignment, and illegal pointer changes are also detected and reported by the Pointer Interpreter block via register bits. An invalid NDF code is any NDF code that does not match the NDF enabled or NDF disabled definitions. The third occurrence of equal new_point indications (3 x eq_new_point) is reported as a discontinuous change of pointer alignment event (DISCOPA) instead of a new pointer event and the active offset is updated with the receive pointer value. An illegal pointer change is defined as

ainc_ind or dec_ind indication that occurs within three frames of the previous inc_ind, dec_ind or NDF_enable indications. Illegal pointer changes may be optionally disabled via register bits.

The active offset value is used to extract the path overhead from the incoming stream and can be read from an internal register.

10.5.2SPE Timing

The SPE Timing Block provides SPE timing information to the Error Monitor and the Extract blocks. The block contains a free running timeslot counter that is initialized by a J1 byte identifier (which identifies the first byte of the SPE). Control signals are provided to the Error Monitor and the Extract blocks to identify the Path Overhead bytes and to downstream circuitry to extract the ATM cell payload.

10.5.3Error Monitor

The Error Monitor Block contains two 16-bit counters that are used to accumulate path BIP-8 errors (B3), and far end block errors (FEBEs). The contents of the two counters may be transferred to holding registers, and the counters reset under microprocessor control.

Path BIP-8 errors are detected by comparing the path BIP-8 byte (B3) extracted from the current frame, to the path BIP-8 computed for the previous frame.

FEBEs are detected by extracting the 4-bit FEBE field from the path status byte (G1). The legal range for the 4-bit field is between 0000 and 1000, representing zero to eight errors. Any other value is interpreted as zero errors.

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