PM7329 S/UNI-APEX-1K800
DATASHEET
PMC-2010141
ISSUE 2
ATM TRAFFIC MANAGER AND SWITCH
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
66
Service Arbitration
Congestion Control
Statistics
Cell Queuing (VC Scheduling)
Class Scheduling
Watch Dog: VC time out patrol and re-allocation
Microprocessor queue buffer re-allocation
10.9.1 Service Arbitration
There are 9 components that request services from the queue engine. Three
components (SAR Rx, WAN Rx, and Loop Rx) can request a cell to be en-
queued. Another three components (SAR Tx, WAN Tx, and Loop Tx) can
request a cell to be de-queued. The shaper, if enabled, can request the
transmission slots to be advanced (see section on Shape Fair Queuing). There
are two possible requests from the watch dog, one to patrol a range of VC
queues to detect a timed out VC, and another request to re-allocate buffers from
a VC that has timed out. The uP can request a VC or Class queue to have their
buffers re-allocated and removed from service. The queue engine is capable of
simultaneously servicing any one or all of the requests from an en-queue
component, a de-queue component, watch dog patrol and transmission slot
advancement. The queue engine is capable of servicing the re-allocation of
buffers from either the uP or watch dog alone. To resolve all these requests,
there are four arbitration units. See Figure 12.