PXF4336 Datasheet, PDF (88/425 Pages) Infineon Technologies AG – ABM Premium ATM Buf fer Manager

ABM-P
PXF 4336 V1.1
Functional Description
rate
PCR
rate
PCR
MBS
SCR
Input Burst
SCR
time
time
Leaky Bucket Shaper Output
Figure 3-27 Ideal ABM-P Shaper Output
The implementation of the combined shaper guarantees sending the MBS as fast as
possible without exceeding the PCR.
If several cell streams are shaped simultaneously, it may happen that cells from different
shapers would have to be sent out at the same cell slot. If N cell streams are shaped, in
rare cases, a cell may have to wait up to N-1 cell cycles for transmission. This temporary
loss of rate is compensated for by slightly stretching the burst in time.
The additional CDV introduced to the PCR by this effect is monitored. With parameter
CDVMax an upper limit on the CDV than can occur without notice is programmed. If this
value is exceeded, an interrupt is generated. “UCDV/DCDV” on Page 288 provides the
details.
The difference between ideal and real shaper output is shown in Figure 3-28
rate
PCR
rate
PCR
Average rate ≤ PCR
MBS
SCR
SCR
time
MBS
Average rate = SCR
time
Ideal
Real
Figure 3-28 Ideal and Real ABM-P Shaper Output
Data Sheet
88
2001-12-17