PXF4333 Datasheet, PDF (84/361 Pages) Infineon Technologies AG – ABM 3G ATM Buf fer Manager

ABM-3G
PXF 4333 V1.1
Functional Description
Table 3-29 summarizes the parameters needed for combined PCR and SCR shaping.
Table 3-29 Summary of VBR Shaping Parameters
Parameter
Derived
from
Stored in
Table/
Register
Range
Min.
Value
Max Value
TP
1/PCR AVT:TP
16 bit
*)
65471
TS
1/SCR AVT:TS
16 bit
*)
65471
tauS
MBS or AVT:tauS
16 bit
0
BT
64511
VBR2.3
AVT:Config 1 bit
0
1
CDVMax
UCDV/DCDV 8 bit
16 cell
cycles
255 x 16 cell
cycles
*) Refer to Table 4.2.2.5f for an explanation of shaper parameter ranges and
granularities.
3.4.2.4.3 Shaping for VBR conformance
The standards define three conformance definitions for rt-VBR and nrt-VBR, referred to
as VBR.1, VBR.2 and VBR.3. Table 3-30 explains the differences between the three
VBR conformance definitions in terms of the relevant cell stream: index 0+1 denotes
both CLP=0 and CLP=1 cells while index 0 denotes CLP=0 cells only.
Table 3-30 VBR Conformance Definitions
PCR Conformance
SCR Conformance
VBR.1
VBR.2
VBR.3
GCRA(PCR₀₊₁, CDVT_PCR)
GCRA(PCR₀₊₁, CDVT_PCR)
GCRA(PCR₀₊₁, CDVT_PCR)
GCRA(SCR₀₊₁, BT)
GCRA(SCR₀, BT)
GCRA(SCR₀, BT),
non conforming CLP=0 cells may be
tagged (CLP set to 1)
Hence, from a shaping perspective, there is no difference between VBR.2 and VBR.3.
As a consequence, the leaky bucket shaper in the ABM-3G is configurable on a per
queue basis to shape either the CLP=0+1 cell stream (config parameter VBR2,3 = 0) or
alternatively the CLP=0 cell stream only (config parameter VBR2,3 = 1). The PCR limiter
always shapes the CLP=0+1 cell stream.
By enabling a Leaky Bucket Shaper with the parameters TP=1/PCR, TS=1/SCR, tau =
BT and VBR2,3 = (0|1), the ABM-3G can be used to produce conforming VBR traffic.
Data Sheet
84
2001-12-17