CN8237EBGB Mindspeed Technologies, CN8237EBGB Datasheet - Page 137

• Manufacturer Part Number: CN8237EBGB
• Description: ATM SAR 622Mbps 3.3V ABR/CBR/GFR/UBR/VBR 456-Pin BGA
• Manufacturer: Mindspeed Technologies

Specifications of CN8237EBGB

• Package: 456BGA
• Traffic Class: ABR|CBR|GFR|UBR|VBR
• Utopia Type: Level 1|Level 2
• Host Interface: PCI
• Maximum Data Rate: 622 Mbps
• Typical Operating Supply Voltage: 3.3 V
• Minimum Operating Supply Voltage: 3.135 V

CN8237
ATM OC-12 ServiceSAR Plus with xBR Traffic Management
5.6.2 Status Queue Overflow or Full Condition
5.7.1 Channel Lookup Structures
28237-DSH-001-C
A status queue overflow or full condition is entered when the last available status
queue entry is written. The reassembly coprocessor detects the condition by
comparing the WRITE and READ_UD index pointers in the corresponding status
queue base table. Upon detecting a status overflow condition, the RSM
coprocessor sets the internal OVFL bit in the last status queue entry written to a
logic high to indicate the condition. To prompt an interrupt, the RSM coprocessor
also sets to 1 the RSM_HS_FULL bit in the HOST_ISTAT1 register.
cells. If a COM or EOM cell is received while the status queue is full, the channel
is marked for status full packet discard. Once an SSM, EOM, or OAM cell is
received during a status full condition, the cell is discarded and the status queue
checked. If there is now room in the status queue, the status full condition is
exited.
the user to detect the full condition and advise the peers to check if their queues
have overflowed. Each peer would then check the OVFL bit in the last status
queue entry written (pointed to by READ_UD – 1) to determine if that peer’s
status queue has filled. If the OVFL bit is not set to a logic high, the host should
also check the entry pointed to by (READ_UD – 2) to determine if an overflow
condition occurred during a host update of the READ_UD index pointer. Because
the reassembly coprocessor recovers from the overflow condition automatically,
the host does not have to determine which queue overflowed.
performs EPD on channels marked for packet discard due to the status overflow
condition, when a cell is received on any of those channels. Cells up to and
including the next EOM are discarded. Status queue overflow protection can be
globally disabled by setting RSM_CTRL0(RSM_STAT_DIS) to a logic high.
NOTE:
5.7 Reassembly Control and Data Structures
The reassembly coprocessor utilizes a VPI/VCI table index mechanism
employing direct index lookup in order to assign each arriving cell to a virtual
channel, based on its VPI/VCI value.
mechanism.
While the reassembly coprocessor is in status full condition, it discards all
For multiple peer configurations, an interrupt manager can be configured by
After a status group has exited a full condition, the RSM coprocessor
Avoid having the Status Queue Overflow (or Full Condition) and DMA
FIFO Buffer Full conditions at the same time.
Mindspeed Technologies
Figure 5-15
™
5.7 Reassembly Control and Data Structures
illustrates this lookup
5.0 Reassembly Coprocessor
5-29