RS8234 Mindspeed Technologies, RS8234 Datasheet - Page 94

• Manufacturer Part Number: RS8234
• Description: Atm Servicesar Plus With Xbr Traffic Management
• Manufacturer: Mindspeed Technologies

4.0 Segmentation Coprocessor
4.3 Segmentation Control and Data Structures
4-16
Table 4-6. Segmentation VCC Table Entry - AAL3/4, 5, and 0 Field Descriptions (2 of 2)
RUN
NX_EOM
CURR_PNTR
SCH
BCK_PM
VPC
SCH_GFR/
CBR_W_TUN
FLOW_ST
GFR_PRI
SCH_MODE
PRI
SCH_OPT
SCH_STATE
NEXT_VCC
Field Name
Flag that indicates that segmentation is proceeding. This flag is set to one by the SAR when the
host supplies data for the VCC; it is set to zero by the SAR when the data available for the VCC is
not sufficient to send at entire ATM cell.
Indicates that the next cell is the end of a CPCS-PDU.
Pointer to the current buffer descriptor for the VCC. This field is automatically updated by the
SAR. The two least significant bits of the pointer are assumed to be zero (word-aligned). The
address of the descriptor is (CURR_PNTR << 2) or (CURR_PNTR * 4).
Indicates VCC is currently scheduled for segmentation.
Toggled after each backward reporting PM cell is scheduled. Used to prevent PM information in
PM table from being overwritten before cell sent.
On a VCC with SCH_MODE = ER, indicates a VPC (Virtual Path Connection) instead of VCC
connection, and RM cells will be generated on VCI=6.
If SCH_MODE = GFR, this bit set to a logic high indicates that the VCC is currently scheduled on a
GFR_PRI priority queue for segmentation. The SCH bit set to a logic high indicates that the VCC is
currently scheduled on a VBR priority queue. The Host does not have to set this bit - it is set by
the SAR.
If SCH_MODE = CBR, this bit set to a logic high specifies that an unused CBR schedule slot
should be used as a tunnel slot, with tunnel priorities specified in word 7 of the VCC table entry.
Flow control state. This bit is active only in ER mode. Indicates that the priority of the connection
is increased to insure MCR.
Specifies the UBR priority level for a GFR service connection. GFR_PRI must be < PRI
Traffic class of VCC. (See
000 UBR - Unspecified Bit Rate
001 CBR - Constant Bit Rate
010 Reserved
011 GFR - Guaranteed Frame Rate
100 VBR1 - Single Leaky Bucket VBR
101 VBR2 - Dual Leaky Bucket VBR with both buckets always active
110 VBRC - Dual Leaky Bucket VBR with bucket 1 applied only to CLP=0 cells
111 ABR - Available Bit Rate (as specified by TM 4.1)
Segmentation priority. The lowest priority is zero. The highest priority is fifteen. This field is not
active when SCH_MODE is CBR. When SCH_MODE is GFR, this specifies the VBR priority.
Schedule option. The use of this bit depends on the setting of the SCH_MODE field.
VBR1, VBR2, VBRC, ER: Initializes bucket state to send maximum burst. The SAR writes this bit
to zero after bucket state initialized.
CBR: Indicates that the next cell slot opportunity should be skipped. This bit is written by the host
and cleared by the SAR after the cell slot is skipped.
If this bit is changed while the VCC is active, only the byte containing the bit should be written.
See the Traffic Management Chapter for details.
Specific scheduling state information. The contents of this field depend on the setting of the
SCH_MODE field. It is not used when SCH_MODE is set to UBR. (The contents of this field are
detailed in
Used by SAR to link VCCs in schedule chains.
Chapter
Mindspeed Technologies
6.0.)
Chapter 6.0
for details.)
Description
ATM ServiceSAR Plus with xBR Traffic Management
™
28234-DSH-001-B
RS8234