![](http://datasheet.mmic.net.cn/380000/-PD98501_datasheet_16745028/-PD98501_336.png)
CHAPTER 4 ATM CELL PROCESSOR
336
Preliminary User’s Manual S14767EJ1V0UM00
4.8.5.3 ABR parameter
Table 4-7. ABR Parameter
Label
Description
Units and Range
PCR
The Peak Cell Rate.
In Cells/Sec, See
Note
for Range
MCR
The Minimum Cell Rate.
In Cells/Sec, See
Note
for Range
ICR
The Initial Cell Rate.
In Cells/Sec, See
Note
for Range
RIF
Rate Increase Factor, RIF, controls the amount by which the
cell transmission rate may increase upon receipt of an RM-
cell.
RIF is power of two, ranging from
1/32768 to 1.
Nrm
Nrm is the maximum number of cells a source may send for
each forward RM-cell.
Power of 2
Range: 2 to 256 cells
Mrm
Mrm controls allocation of bandwidth between forward RM-
cells, backward RM-cells, and data cells.
Power of 2
range: 1 to 8 cells
RDF
The Rate Decrease Factor, RDF, controls the decrease in the
cell transmission rate.
RDF is from 2 to 1/32,768
ACR
The Allowed Cell Rate, ACR, is the current rate at which a
source is allowed to send.
In Cells/Sec, See
Note
for Range
CRM
Missing RM-cell count. CRM limits the number of forward RM-
cells which may be sent in the absence of received backward
RM-cells.
Units: cells.
Integer.
ADTF
The ACR Decrease Time Factor is the time permitted
between sending RM-cells before the rate is decreased to
ICR.
Units: seconds
ADTF range: .01 to 10.23sec with
granularity of 10ms.
Trm
Trm provides an upper bound on the time between forward
RM-cells for an active source.
Trm is 100 times a power of two
range: 100*2
-7
to 100*2
0
FRTT
The Fixed Round Trip Time, FRTT, is the sum of the fixed
and propagation delays from the source to the furthest
destination and back.
Units 10 microseconds
Range: 0 to 167 seconds
TBE
Transient Buffer Exposure, TBE, is the negotiated number of
cells that the network would like to limit the source to sending
during idle startup period, before the first RM-cell returns.
Units: Cells
Range: 0 to 16,777,215
CDF
The Cutoff Decrease Factor, CDF, controls the decrease in
ACR associated with CRM.
CDF is zero, or power of two in the
range 1/64 to 1.
TDF, ADDF
The Timeout Decrease Factor, TDF, controls the decrease in
ACR associated with TOF. TDF is signaled as ADDF(ACR
Decay Decrease Factor), where TDF = ADDF times the
smallest power of 2 in cells/second greater than or equal to
ICR in cells/second.
TDF is in units of 1/seconds. ADDF is
either zero or a power of two in the
range 2
-5
to 2
-19
PNI
The Permit Next Increase flag, PNI. PNI=1 disables source
behavior 5b. PNI=0 enables source behavior 5b.
0 or 1.
TCR
The Tagged Cell Rate, TCR, limits the rate at which a source
may send out-of-rate forward RM cells.
TCR is a constant fixed at 10
cells/second
Note
Rate field is expressed as below.
Rate = 2
e
*(1+m/512)*nz cells/sec