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IBM2520L8767
IBM Processor for ATM Resources
atmrm.chapt03.01
08/27/99
Packet Header
Page 51 of 553
PCR_delta_valid
This one-bit field is set by the hardware to indicate that the 36-bit PCR delta field is valid. After initializa-
tion, this field should only be accessed by the hardware.
PCR_delta
This 36-bit field is set by the hardware the first time a PCR-containing transport stream packet is
encountered by the segmentation logic. The high 36 bits of the PCR in the packet, along with an inter-
nal time base, are used to determine a PCR delta for future use. After initialization, this field should only
be accessed by the hardware.
explicit_rate
This 16-bit field contains the explicit cell rate as defined for ABR traffic on this LCD.
current_rate
This 16-bit field contains the current cell rate as defined for ABR traffic on this LCD.
minimum_rate
This 16-bit field contains the minimum cell rate as defined for ABR traffic on this LCD.
backward_ptr
When software needs to send a backward RM cell, this 32-bit field should be updated with the address
of a buffer that contains the desired backward RM cell. After the segmentation logic transmits the cell,
this field will be cleared by the hardware.
total_user_cells
This 32-bit field contains a count of the total number of user cells that have been sent on this LCD, after
either statistics or blocking are enabled either globally or locally for this LCD. This field should be set to
zero when the connection is initialized. An event will be generated when this count wraps.
total_user_cells_CLP0
This 32-bit field will contain a count of the total number of user cells that have been sent on this LCD
with CLP = 0, if either statistics or blocking are enabled either globally or locally for this LCD. This field
should be set to zero when the connection is initialized. An event will be generated when this count
wraps. When configured, this field can also be total packets transmited.
threshold_1&2
These fields are compared to the upper 24 bits of the bytes_queued field to determine when a thresh-
old is crossed and the pool ID for the received LCD should be changed.
pool_id1&2
These fields are used to change the POOL ID when a threshold is crossed.
bytes_queued
This field is used to keep track of the number of bytes queued for transmission on this LCD.
timer_type #
These encoded bits determine the time of timer.
00 = relative non-periodic timer
The expiration time will be in one timer period. The timer will not be
scheduled again automatically.
The expiration time will be in 1 timer period. The timer will be auto-
matically scheduled again .
01 = relative periodic timer
10 = absolute non-periodic timer The timer will expire at the time specified by the timestamp field. The
timer will not be automatically scheduled again .
11 = absolute periodic timer
The timer will expire at the time specified by the timestamp field. The
timer will be scheduled again, automatically, using the time specified
in the timer_period field.
timer_period #
This field specifies the number of timeslots before the timer expires.
dma_desc_addr #
The DMA descriptor pointed to by this field will be queued for execution when the timer expires.
CRM
Missing RM-cell count. CRM limits the number of forward RM-cells which may be sent in the absence
of received backward RM-cells. CDF is written to the NCRM field whenever a backward RM cell is
detected.
iCDF
Cutoff Decrease Factor (CDF) controls the decrease in ACR associated with CRM. CDF is zero or a
power of 2 value in the range of 1/64 to 1. iCDF represents the power of 2 that is in the denominator of
CDF. CDF = 1/(2**iCDF) so iCDF = log (base 2) of 1/CDF. Range = 1 to 6. A zero value for CDF should
be represented as 0xFF for iCDF.
ABR Code Variables Definitions
(Page 6 of 7)
Field Name
Field Description