CN8237EBGB Mindspeed Technologies, CN8237EBGB Datasheet - Page 53

• Manufacturer Part Number: CN8237EBGB
• Description: ATM SAR 622Mbps 3.3V ABR/CBR/GFR/UBR/VBR 456-Pin BGA
• Manufacturer: Mindspeed Technologies

Specifications of CN8237EBGB

• Package: 456BGA
• Traffic Class: ABR|CBR|GFR|UBR|VBR
• Utopia Type: Level 1|Level 2
• Host Interface: PCI
• Maximum Data Rate: 622 Mbps
• Typical Operating Supply Voltage: 3.3 V
• Minimum Operating Supply Voltage: 3.135 V

CN8237
ATM OC-12 ServiceSAR Plus with xBR Traffic Management
2.5.6 xBR Cell Scheduler
28237-DSH-001-C
The xBR Scheduler slates traffic for transmission according to a Dynamic
Schedule table maintained in SEG memory. The table contains a
user-programmable number of schedule slots. The duration of a single slot is a
user-programmable number of system clock cycles. The xBR Scheduler
sequences through this table in a circular fashion to schedule traffic. By
configuring the number of slots in the table and the duration of each slot, the
system designer chooses a range of available rates. A specific rate for any channel
is determined by how many slots in the table to which that channel is assigned.
Schedule slots not reserved for CBR during table setup are used for the rest of the
service categories.
rate-shaping algorithms. The predecessor to the CN8237, the Bt8230 SAR,
proved the core algorithms. The CN8237 extends their use to other service
classes. The CN8237 xBR Scheduler shapes all traffic classes, including CBR,
single leaky bucket VBR, dual leaky bucket VBR, ABR, and UBR. The host
configures the Dynamic Schedule table during system initialization, defining the
table size in number of schedule slots and the length of each schedule slot in clock
cycles. After setup, the CN8237 dynamically manages the entire table.
without host intervention. The CN8237 fairly distributes the link bandwidth to
channels based upon their QoS parameters and assigned transmission priority. As
covered previously, the CN8237 supports 16 priorities in addition to preallocated
CBR time slots.
topologies. The CN8237 rate shapes VCs or VPs. Additionally, CBR tunneling
allows UBR, VBR and/or ABR traffic management schemes to operate under a
preallocated CBR limit.
The xBR Scheduler implements Mindspeed’s proprietary per-VCC
Some key features of the xBR Scheduler are as follows:
1.
2.
3.
4.
5.
6.
Dynamic management provides on-the-fly reallocation of link bandwidth
The xBR Scheduler facilitates advanced network traffic management
Per-VCC rate control guarantees conformance to GCRA UPC/policing
Dynamic reallocation of link bandwidth to active channels
Dynamic, fair sharing of bandwidth on oversubscribed lines
Multiple scheduling priorities
Fine grained rate control
Rate based on a user supplied reference clock
Mindspeed Technologies
™
2.5 Advanced xBR Traffic Management
2.0 Architecture Overview
2-19