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IBM2520L8767
IBM Processor for ATM Resources
atmrm.chapt03.01
08/27/99
Packet Header
Page 67 of 553
LCD Raw Mode Field Definitions
Field Name
Field Description
Note
mode
This field selects the major mode for this LCD. The other fields are based on this value.
00 = Normal
01 = Routed
10 = Cut Thru
11 = FIFO Mode
1
size
This field specifes how many bytes are stored when cell is received.
00 = 53-Byte cell
01 = Byte cell (no HEC)
10 = 48-Byte cell
11 = 48-Byte cells (contiguous mode in FIFO mode only)
1
storeCrc10
When set, the CRC-10 state bit is written into the packet header. A one is written in the error status bit in
word 0 if a bad CRC-10 is detected.
1
earlyDrop
When set, the cells for this LCD are assumed to form an AAL5 stream; early drop mode is enabled.
1
routeNud
When set, non-user data cells are routed just like other routed cells. When cleared, non-user data cells are
terminated at this node.
1
routedLcd
When routing cells, this field is used to fill in the LCD field of the packet header. This allows the user to
dynamically route cells back out the interface using a different LCD. The user should be sure to set the free
on transmit bit in this field as if it was in a packet header.
1
fifoThresh
Specifies how many cells should be received in the receive FIFO before a FIFO threshold event should be
surfaced. If this field is set to zero, no threshold events are surfaced.
1
fifoSizeMask
Used by RAALL to determine how large the FIFO buffer is.
SizeField (15-6)
FIFO Size
0000000000
64 bytes
0000000001
128 bytes
0000000011
256 bytes
0000000111
512 bytes
0000001111
1K bytes
0000011111
2K bytes
0000111111
4K bytes
0001111111
8K bytes
0011111111
16K bytes
0111111111
32K bytes
1111111111
64K bytes
64-Byte cells
1
2
4
8
16
32
64
128
256
512
1K
48-Byte cells
1
2
5
10
21
42
85
170
341
682
1365
1
baseAddr
Specifies the base address of the FIFO buffer at initialization. Once enabled, RAALL uses this field to
maintain a pointer to where the next cell is to be received.
1
maxCellCnt
Specifies the maximum number of cells that the FIFO buffer should contain. This does not need to be the
maximum specified by the buffer size.
1
currRxCellCnt
Specifies how many cells have been received into the FIFO since the last threshold was crossed. This
should be initialized to zero. After initialization, RAALL maintains this field.
1
totalRxCellCnt
Specifies how many active cells are contained in the FIFO (cells not acknowledged by user). This should
be initialized to zero. After initialization, RAALL maintains this field.
1
1. Software should set up this field.