cn8237 Mindspeed Technologies, cn8237 Datasheet - Page 27

• Manufacturer Part Number: cn8237
• Description: Atm Oc-12 Servicesar Plus With Xbr Traffic Management
• Manufacturer: Mindspeed Technologies

28237-DSH-001-C
1.0 CN8237 Product Overview
1.1 Introduction
The CN8237 Service Segmentation and Reassembly Controller (ServiceSAR)
delivers, at OC-12 rates, a wide range of advanced ATM and AAL functions in a
single highly-integrated CMOS package. The CN8237 ServiceSAR also delivers
service-specific features that enable system designers to accelerate specific
protocol interworking functions. These features include:
Forum Traffic Management Specification, TM 4.1. The CN8237 provides
traffic-shaping for all service categories, including:
The internal xBR Traffic Manager automatically schedules each VCC according
to user-assigned parameters.
host manages the CN8237 terminal with an efficient architecture that uses
write-only control and status queues. For example, the host submits data for
transmit by writing buffer descriptor pointers to one of 32 transmit queues. These
entries form lists of tasks for the ServiceSAR to perform. The CN8237 reports
segmentation and reassembly status to the host by writing entries to segmentation
and reassembly status queues, which the host processes. This architecture lessens
the control burden on the host and minimizes Peripheral Component Interconnect
(PCI) bus utilization by eliminating host control activities across the PCI bus.
• Frame Relay Early Packet Discard (EPD)
• Generic Flow Control (GFC)
• Echo suppression of multicast data frames on Emulated LAN (ELAN)
The CN8237 meets the requirements of UNI 3.1 and complies with ATM
• Constant Bit Rate (CBR)
• Variable Bit Rate (VBR)—both single and dual leaky bucket
• Unspecified Bit Rate (UBR)
• Available Bit Rate (ABR)
• GFC—both controlled and uncontrolled flows
• Guaranteed Frame Rate (GFR), that is, guaranteed Minimum Cell Rate
The CN8237 architecture minimizes and controls host traffic congestion. The
(MCR) on UBR Virtual Channel Connections (VCCs)
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