Motorola MPC8260 - Manual (Page 811)

29-31 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA
Part IV. Communications Processor Module
BEDC is calculated. When an FMC is received, the CP adds the BRC Þelds into the cell
payload (TRCC
0
, TRCC
0+1
, BLER) and transfers the cell to the receive raw cell queue. The
user can monitor the BRC cell results and transfer the cell to the transmit raw cell queue.
Before the BRC is transferred to the transmit raw cell queue, the PM function type should
be changed to backward reporting and additional checking should be done regarding the
BLER Þeld. If the sequence numbers (MCSN) of the last two FMCs are not sequential or
the differences between the last two TUCs and the last two TRCCs are not equal, BLER
should be set to all ones (see the ITU I.610 recommendation).
Note that the TRCCs are free-running counters (modulo 65,536) that count user cells
received. The total received cells of a particular block is the difference between TRCC
values of two consecutive BRC cells. TRCC values are taken from a VCÕs performance
monitoring table.
29.6.6.3 PM Block Generation
The transmitter generates the PM block. Each time the transmitted cell count parameter
(TCC) in the performance monitoring table reaches zero, the CP inserts an FMC into the
user cell stream. The CP copies the FMC header, SN-FMC, TUC
0+1
, TUC
0
, BEDC
0+1
-Tx
from the performance monitoring table and inserts them into the FMC payload. The TSTP
value (FMC time stamp Þeld) is taken from the MPC8260 time stamp timer; see
Section 13.3.7, ÒRISC Time-Stamp Control Register (RTSCR).Ó
The TUCs are free-running counters (modulo 65,536) that count transmitted user cells. The
total transmitted cells of a particular block is the difference between TUC values of two
consecutive FMCs. The BEDC (BIP-16, bit interleaved parity) calculation is done on the
payload of all user cells of the current tested block. The performance monitoring block can
range from 1 to 2K cells, as speciÞed in the BLCKSIZE parameter in the performance
monitoring table; see Section 29.10.3, ÒOAM Performance Monitoring Tables.Ó
In Figure 29-18, the performance monitoring block size is 512 cells. For every 512 user
cells sent, the ATM controller automatically inserts an FMC into the regular cell stream as
deÞned in ITU I.610. When an FMC is received, the ATM controller adds the BRC Þelds
to the cell payload and sends the cell to the raw cell queue. The user can monitor the BRC
cell results and transfer the cell to the transmit raw cell queue.