PM7329 S/UNI-APEX-1K800
DATASHEET
PMC-2010141
ISSUE 2
ATM TRAFFIC MANAGER AND SWITCH
Figure 15
- Non-integer ShpIncr
emission
with ShpIncr = 1.5
fundamental time slots
User programming can also define the action of the shaper when overall egress
congestion (i.e. too much traffic being sent through the shaper) is causing all
VCs on that port/class to experience shaping delay due to congestion. When
congestion is detected, the shaper will temporarily increase the fundamental
shaping time unit, thereby causing each VC to schedule cells less frequently.
This will eventually relieve the congestion, at which point the time unit will be
brought back to its previous value. The impact of the congestion is distributed
fairly across all VCs on the congested port because all VCs on the port
experience the same relative decrease in scheduling frequency.
10.9.2.4
Non-User Cell Queuing
When a non-user cell is encountered, it may be queued with special handling.
The cases requiring special handling are:
• Cells identified as an end to end OAM may be redirected to the uP’s class 0
queue. This can occur independent of the queuing mechanism selected for
the VC (WFQ, FCQ, and SFQ).
• Cells identified as a segment OAM may be redirected to the uP’s class 0
queue. This can occur independent of the queuing mechanism selected for
the VC (WFQ, FCQ, and SFQ).
• During FCQ, a cell identified as an OAM that is not being redirected to the uP
will bypass the VC queue re-assembly area and go directly to the class
queue.
• During FCQ, a cell identified as an RRM (Reserved or Resource
Management) will bypass the VC queue re-assembly area and go directly to
the class queue.
The table below lists the rules used to identify OAM and RRM cell types.
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
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PMC [ PMC-SIERRA, INC ]
