Freescale Semiconductor MPC8260 - Manual (Page 951)

ATM Controller and AAL0, AAL1, and AAL5
MPC8260 PowerQUICC II Family Reference Manual, Rev. 2
Freescale Semiconductor 30-31
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 field. 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
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 VC’s performance monitoring table.
30.6.6.3 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 field) is taken from the
PowerQUICC II time stamp timer; see
Section 14.3.8, “RISC Time-Stamp Control Register (RTSCR).”
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 specified in the
BLCKSIZE parameter in the performance monitoring table; see
Section 30.10.3, “OAM Performance
Monitoring Tables.”
In Figure 30-18 , 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 defined in ITU I.610. When an FMC
is received, the ATM controller adds the BRC fields 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.
Figure 30-18. FMC, BRC Insertion
FMC Cell Data Cell Data Cell FMC Cell Data Cell Data Cell FMC Cell
512 User Cells 512 User Cells
TUC0
Source Cells
Stream
1 2 3
TSTP
BEDC
TUC0+1
TUC0
TSTP
BEDC
TUC0+1
TUC0
TSTP
BEDC
TUC0+1
BRC Cell
TUC0
Destination BRC’s
Transmit Stream
1
TUC0+1
TSTP
BLER
TRCC0
TRCC0+1
BRC Cell
TUC0
2
TUC0+1
TSTP
BLER
TRCC0
TRCC0+1
BRC Cell
TUC0
3
TUC0+1
TSTP
BLER
TRCC0
TRCC0+1