cn8236 Mindspeed Technologies, cn8236 Datasheet - Page 27

• Manufacturer Part Number: cn8236
• Description: Atm Servicesar Plus With Xbr Traffic Management
• Manufacturer: Mindspeed Technologies

28236-DSH-001-B
1.0 CN8236 Product Overview
1.1 Introduction
The CN8236 Service Segmentation and Reassembly Controller (ServiceSAR)
delivers a wide range of advanced ATM, AAL, and service-specific features in a
highly integrated CMOS package.
capabilities of accelerating specific protocol interworking functions. These
features include, for example, Virtual FIFO buffer segmentation of circuit-based
Constant Bit Rate (CBR) traffic and Frame Relay Early Packet Discard (EPD)
based on the Discard Eligibility (DE) field.
Two examples of these features include Generic Flow Control (GFC) and echo
suppression of multicast data frames on Emulated LAN (ELAN) channels.
complies with ATM Forum Traffic Management Specification, TM 4.1. The
CN8236 provides traffic shaping for all service categories:
according to user assigned parameters.
congestion. The host manages the CN8236 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 can be thought of as task lists for the ServiceSAR to perform. The
CN8236 reports segmentation and reassembly status to the host by writing entries
to segmentation and reassembly status queues, which the host then further
processes. This architecture lessens the control burden on the host system and
minimizes Peripheral Component Interconnect (PCI) bus utilization by
eliminating reads across the PCI bus from host control activities.
Some of the CN8236 service-level features provide system designers with
Other service-level functions enable network level functionality or topologies.
In addition to meeting the requirements contained in UNI 3.1, the CN8236
• 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 internal xBR Traffic Manager automatically schedules each VCC
The CN8236’s architecture is designed to minimize and control host traffic
(MCR) on UBR Virtual Channel Connections (VCCs)
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