RS8234EBGC Mindspeed Technologies, RS8234EBGC Datasheet - Page 171

• Manufacturer Part Number: RS8234EBGC
• Description: RS8234EBGC ATM XBR SAR
• Manufacturer: Mindspeed Technologies

RS8234
ATM ServiceSAR Plus with xBR Traffic Management
6.2.3 CBR Traffic
6.2.3.1 CBR Rate
Selection
6.2.3.2 Available Rates
28234-DSH-001-B
APPLICATION EXAMPLE: Determining Maximum Rate
To achieve the maximum rate, the user would assign one VCC to every cell slot in the Schedule Table.
This would prevent any other VCC from being scheduled since this channel uses all of the available
slots.
frequency(SYSCLK) = 33 MHz
SLOT_PER
R
max
= 354.8 K cells/second
The CBR service category guarantees end-to-end bandwidth through the network.
Certain data sources, such as voice circuits, require this guarantee, as well as
constrained Cell Delay Variation (CDV). CDV is a measure of the “burstiness” of
traffic. The ATM network supplies a minimum CDV for CBR channels by
reserving cell transmission opportunities for the connections.
Table to a CBR VCC. This connection will always send a single cell during its
assigned slots. The system clock serves as a time reference for CBR cell
generation. The systems designer programs the duration of schedule slots in
system clocks in the SLOT_PER (slot period) field of the SCH_SIZE register.
Maximum Rate
For each CBR assigned cell slot, the RS8234 generates one cell on the specified
VCC. The maximum or base rate of CBR channels is determined by the duration
of a cell slot according to the equation below, where R
cells per second.
transmit a full cell, and its minimum bound should be no less than 70.
Once a maximum rate
determines the rate granularity and minimum rate. The system designer specifies
the number of table slots in SCH_SIZE(TBL_SIZE). The available CBR rates are:
Minimum Rate
The minimum rate available is therefore
= 93 clocks/slot
The RS8234 generates CBR traffic by assigning specific slots in the Schedule
SLOT_PER should be nominally set to the number of clock cycles needed to
Mindspeed Technologies
R
max
TBL_SIZE, ... ..., R
, R
SLOT_PER
(R
max
max
x(TBL_SIZE –1)/TBL_SIZE, R
)
has been selected, the size of the Schedule Table
=
frequency SYSCLK
----------------------------------------------------- -
max
™
R
6.2 xBR Cell Scheduler Functional Description
max
/TBL_SIZE
/TBL_SIZE
R
max
max
.
max
is the maximum rate in
6.0 Traffic Management
x(TBL_SIZE – 2)/
6-11