Released
Datasheet
PM73487 QRT
PMC-Sierra, Inc.
PMC-980618
Issue 3
622 Mbps ATM Traffic Management Device
7.2.18 TX_QUEUE_ENGINE_TEST
Address: 29h (A4h byte)
Type: Read/Write
Function: The bits in this register disable individual functions within the queue engine
for system debug purposes.
•
The “E” process (the transmit switch fabric Enqueue process) performs the enqueue function for each
cell arrived from the switch process. It determines if a cell is eligible for enqueue (that is, SENT or
DROP) based on current congestion conditions.
•
•
•
The “C” process (the update transmit Counters process) updates the per-channel statistics.
The “M” process (the Multicast replication process) performs the multicast leaf replication task.
The “D” process (the transmit UTOPIA Dequeue process) fetches a cell for transmit UTOPIA transmis-
sion.
Reset Value: 0
Format: Refer to the following table.
Field (Bits)
Description
RESERVED
(31:23)
Write with a 0 to maintain future software compatibility.
TX_SCG_ENABLE
(22)
1
Enforce the Service Class Group congestion limits configured in
TX_LWRxx_EXP_MAX_QD and TX_LWRxx_EXP_CONG_QD.
Note: When this feature is enabled, the maximum queue depth for any of
the three service class groups is 31K cells.
0
1
Ignore the configured SCG congestion limits
TX_RED_ENABLE
(21)
Enable Random Early packet Discard function. The
TX_xxx_EXP_CONG_QD that is used for each of the CH, SCQ, SC,
SCG, VO and DIR settings is randomly chosen to be the user configured
one or the value one codepoint below the configured value.
RED disabled
0
1
TX_CLP_BEFORE_EPD_ENABL
Enable CLP before EPD dropping. When this feature is enabled, CLP=1
cells are dropped at the queue depth defined by the appropriate the code-
point one below that defined in TX_xxx_EXP_CONG_QD triggering
PTD (Packet Tail Dropping). CLP=0 cells are considered for dropping
by the EPD algorithm at the queue depth defined by
TX_xxx_EXP_CONG_QD.
E
(20)
0
1
Disable CLP before EPD dropping.
TX_HYSTERESIS_DISABLE
(19)
Disable TX DIR, VO, SCG, SC and SCQ congestion hyteresis. This set-
ting declares that congestion is relieved when the queue depth drops
below the queue depth defined by the appropriate
TX_xxx_EXP_CONG_QD. This setting might achieve higher through-
put in cases where the incoming traffic characteristics are less bursty.
Enable TX DIR, VO, SCG, SC, and SCQ congestion hysteresis. This
setting declares that congestion is relieved when the queue depth drops
below the queue depth defined by the appropriate the codepoint one
below that defined in TX_xxx_EXP_CONG_QD. This is a more robust
setting which forces the switch to make the most of each dropping event
at the expense of access to cell buffers in the steady state.
0
128
PMC [ PMC-SIERRA, INC ]
