Motorola PowerQUICC II MPC8280 Series Reference Manual page 1048

OAM Support
31.6.6.3 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
from the performance monitoring table and inserts them into the FMC payload. The TSTP
value (FMC time stamp field) is taken from the MPC8280 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 31.10.3, "OAM Performance Monitoring Tables."
In Figure 31-18, 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.
512 User Cells
3
FMC Cell Data Cell
TUC0
TUC0+1
BEDC
TSTP
31.6.6.4 BRC Performance Calculations
BRC reception uses the regular AAL0 raw cell queue. On receiving two consecutive BRC
cells, the management layer can calculate the following:
• The difference between two TUCs (Nt)
• The difference between two TRCCs (Nr)
31-34
Freescale Semiconductor, Inc.
2
Data Cell FMC Cell
TUC0
TUC0+1
BEDC
TSTP
Destination BRC's
Transmit Stream
Figure 31-18. FMC, BRC Insertion
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512 User Cells
Data Cell Data Cell
2
1
BRC Cell BRC Cell
TUC0
TUC0
TUC0+1
TUC0+1
TRCC0
TRCC0
TRCC0+1
TRCC0+1
BLER
BLER
TSTP
TSTP
, TUC , BEDC -Tx
0+1 0 0+1
1
Source Cells
Stream
FMC Cell
TUC0
TUC0+1
BEDC
TSTP
3
BRC Cell
TUC0
TUC0+1
TRCC0
TRCC0+1
BLER
TSTP
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