pxf4336 Infineon Technologies Corporation, pxf4336 Datasheet - Page 49

• Manufacturer Part Number: pxf4336
• Description: Abm Premium Atm Buf Fer Manager
• Manufacturer: Infineon Technologies Corporation

3.2
3.2.1
The Cell Handler (CH) units are responsible for the physical data flow of storing and
retrieving cells to/from the respective Cell Storage RAM or insertion and extraction of
Resource Management (RM) cells. Updates to the cell header section or to the cell
contents in case of OAM-RM cells are also performed by the Cell Handler units.
3.2.2
The Buffer Manager (BM) unit is the central function of the ABM-P device and handles
the logical data flows for upstream and downstream direction. It utilizes the Queue
Scheduler to coordinate cell emission and a common Cell Pointer RAM (SSRAM) to
administrate cell storage.
Any cell entering the CH unit is reported to the BM unit running the cell acceptance
algorithm. In a first step a cell is classified and associated to the logical resource entities
connection, queue, traffic class and scheduler. As an exception Resource Management
(RM) cells are extracted and forwarded to the ERC unit for further processing. Once all
associated resources are determined, the BM runs the cell acceptance algorithm based
on the current parameter sets. As a result of all threshold evaluations the cell is either
discarded or accepted and related counters are updated accordingly. Non-empty
queues are reported to the Queue Scheduler (QS) unit to be scheduled by the
associated calendar. In return the QS unit reports queues to the Buffer Manager that are
due for cell transmission in the current cell slot. Upon a cell emit request for a specific
queue the BM either requests the Cell Handler to retrieve and transmit the next cell or to
insert an RM cell as prepared by the ERC unit.
Since the BM and QS units are the central functions of the ABM-P device they are
described in more detail in chapter
on Page
3.2.3
The Enhanced Rate Control (ERC) unit interfaces to the BM and the CH units for RM cell
insertion and extraction. It controls the following functions on a per connection basis:
• ABR-VS/VD: Processing of RM cells, related state machines and rate adjustment
• ABR-ER: Rate calculation and RM cell processing (and adjustment in case of RSC)
The ERC unit is described in more detail in section
on Page
Data Sheet
64.
110.
Functional Block Description
Cell Handler (Upstream/Downstream)
Buffer Manager and Queue Scheduler (Overview)
Enhanced Rate Control Unit Overview
“Buffer Manager and Queue Scheduler Details”
49
“ERC Unit Functional Overview”
Functional Description
PXF 4336 V1.1
2001-12-17
ABM-P