Released
Datasheet
PM73487 QRT
PMC-Sierra, Inc.
PMC-980618
Issue 3
622 Mbps ATM Traffic Management Device
9.3.1.7 TX_CH_CONFIG
Address: Ah (28h byte)
Type: Read/Write
Format: Refer to the following table.
Field (Bits)
Description
TX_CH_EXP_MAX_QD
(31:28)
Exponent of the maximum per-SC queue depth. Initialize to the proper setting. Limits the
TX_CH_CUR_QD to:
TX_CH_CUR_QD ≤ 1 + 2TX_CH_EXP_MAX_QD
A value of 0h causes all cells for this channel to be dropped. A value of Fh limits this chan-
nel to 31744 cells.
TX_CH_EXP_CONG_QD
(27:24)
Exponent of the congested per-SC queue depth. Initialize to the proper setting. The con-
gestion state is entered when the threshold is exceeded, and the congestion state is exited
when the queue length drops below 50 percent of this threshold. Enables congestion man-
agement when:
TX_CH_CUR_QD > 1+2TX_CH_EXP_CONG_QD
A value of 0h causes this CH to be in congestion at all times. A value of 1h may not be
used. A value of Fh causes this CH to enter congestion at a depth of 31744 cells.
TX_CH_ENTRY_PRESENT
(23)
Initialize to 0, set other variables, then initialize to the proper setting.
1
0
Indicates this channel is present and valid.
Indicates this channel is disabled. Drop any cells received at this index, but
still update TX_CH_CELLS_SENT and TX_CH_CELLS_DRPD (refer to
sections “TX_CH_CELLS_SENT” on page 193 and
“TX_CH_CELLS_DRPD” on page 193).
Not used
(22:20)
Write with a 0 to maintain software compatibility with future versions.
TX_CH_SERVICE_CLASS
(19:16)
Indicates the transmit SC.
TX_CH_EN_CLP_DROP
(15)
Initialize to the proper setting.
1
Enables CLP dropping when the channel, the SC, the SSC, the VO, or the
device is in the congested state.
0
Disables CLP dropping above the congestion threshold.
Not used
(14)
Write with a 0 to maintain software compatibility with future versions.
TX_CH_EN_AAL5_EPD
(13)
Initialize to the proper setting.
1
0
Enables AAL5 Early Packet Discard (EPD) when the channel, the SCQ, the
SC, the VO, or the device is in the congested state. If the queue depth reaches
the maximum threshold, or if CLP = 1 and the queue depth reaches the con-
gestion threshold, the tail of the frame is dropped.
Disables AAL5 EPD.
TX_CH_EN_EFCI
(12)
Written with a 0 to maintain compatibility with future software versions.
1
0
Enable EFCI.
Disable EFCI.
Reserved
(11:8)
Initialize to 0 at initial setup. Software modifications to these locations after setup may
cause incorrect operation.
189
PMC [ PMC-SIERRA, INC ]
