Freescale Semiconductor MPC8260 - Manual (Page 953)

ATM Controller and AAL0, AAL1, and AAL5
MPC8260 PowerQUICC II Family Reference Manual, Rev. 2
Freescale Semiconductor 30-33
30.8 ATM Layer Statistics
ATM layer statistics can be used to identify problems, such as the line-bit error rate, that affect the UNI
performance. Statistics are kept in three 16-bit wrap-around counters:
• UTOPIA error dropped cells count—Counts cells discarded due to UTOPIA errors: Rx parity
errors and short or long cells.
• Misinserted dropped cell count—Counts cells discarded due to address look-up failure.
• CRC10 error dropped cell count—Counts cells discarded due to CRC10 errors. (ABR only).
Counters are implemented in the dual-port RAM for each PHY device. The counters of each PHY are
located in the UNI statistics table, described in
Section 30.10.7, “UNI Statistics Table.”
30.9 ATM-to-TDM Interworking
The PowerQUICC II supports ATM and TDM interworking. The MCCs and their corresponding SIs
handle the TDM data processing. (See
Chapter 28, “Multi-Channel Controllers (MCCs),” and Chapter 15,
“Serial Interface with Time-Slot Assigner.” ) The ATM controller processes the ATM data.
Possible interworking applications include the following:
• Circuit emulation service (CES)
• Carrying voice over ATM
• Multiplexing several low speed services, such as voice and data, onto one ATM connection
Data forwarding between the ATM controller and an MCC can be done in two ways:
• Core intervention. When an MCC receive buffer is full and its RxBD is closed, the MCC interrupts
the core. The core copies the MCC’s receive buffer pointer to an ATM TxBD and sets the ready bit
(TxBD[R]). Similarly, when an ATM receive buffer is full and its RxBD is closed, the core services
the ATM controller’s interrupt by copying the ATM receive buffer pointer to an MCC TxBD and
setting TxBD[R]. This mode is useful when additional core processing is required.
• Automatic data forwarding. This mode enables automatic data forwarding between AAL1/AAL0
and transparent mode over a TDM interface.
30.9.1 Automatic Data Forwarding
The basic concept of automatic data forwarding is to program the ATM controller and the MCC to process
the same BD table, as shown in
Figure 30-21 .
16-bit 4-bit 12-bit 16-bit
CAM data in field: UEAD PHY addr VPI VCI
0 15 16 19 20 31 32 47
Figure 30-20. External CAM Address in UDC Extended Address Mode