T8207 Datasheet, PDF (121/158 Pages) Agere Systems – ATM Interconnect

Advance Data Sheet
September 2001
CelXpres T8207
ATM Interconnect
14 Registers (continued)
Table 96. PPD Information 4 (PPDI4) (020Ch)
Name
ppd_pnt6_sel[5:0]
ppd_pnt7_sel[5:0]
Reserved
Bit Pos. Type Reset
Description
5:0 RW X PPD Pointer 6 Select.
The ppd_pnt6_sel[5:0] bit field selects which bit of the cell header,
the cell bus routing header, or the tandem routing header is used
as this offset bit.
11:6 RW
X PPD Pointer 7 Select.
The ppd_pnt7_sel[5:0] bit field selects which bit of the cell header,
the cell bus routing header, or the tandem routing header is used
as this offset bit.
15:12 RO
PPD Pointer 6 and 7 Select.
The ppd pointer select bits are used to create an offset into the
PPD state memory. The PPD state memory is used to keep track
of AAL5 virtual channels for partial packet discard. Up to 8192 vir-
tual channels may be supported with these select fields. The
ppd_pnt12_sel[5:0] bits select the most significant bit of the PPD
state memory offset, and the ppd_pnt0_sel[5:0] bits select the
least significant bit of the offset. A value of zero to 31 selects bits
in the cell header where zero is the CLP bit and 31 is the most
significant bit of the GFC/VPI field. A value of 32 to 47 selects bits
in the tandem routing header where 32 is the least significant bit
and 47 is the most significant bit. A value of 48 to 63 selects bits
in the cell bus routing header where 48 is the least significant bit
and 63 is the most significant bit. The value, “110000,” is a special
case and may be used to force the value of this bit to ‘0.’ If this bit
is forced to zero, the bit position in the resultant pointer is always
‘0’ and is not extracted from the received cell.
0 Reserved.
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