Quality of Service Guide QoS and QoS Policies
Edition: 01 3HE 11014 AAAC TQZZA 83
Figure 17 Access Ingress Scheduling for 4-Priority and 16-Priority SAPs
(with Per-SAP Aggregate Shapers)
The 16-priority scheduler can be used without setting an aggregate rate limit for the
SAP, in which case traffic out of the SAP queues are serviced in strict priority order,
the conforming traffic prior to the non-conforming traffic. Using 16-priority schedulers
without a configured per-SAP aggregate shaper (PIR = maximum and CIR = 0 kb/s)
might be preferred over 4-priority mode for the following reasons:
• coherent scheduler behavior across SAPs (one scheduler model)
• ease of configuration
As indicated in Figure 17, all the traffic leaving from the shaped SAPs must be
serviced using 16-priority scheduling mode.
CoS-8
CoS-1
CoS-7
CoS-8
CoS-1
CoS-7
4-priority Scheduled
Unshaped SAPs
16-priority Scheduled
Shaped or
Unshaped SAPs
Buffer Mgmt
via WRED
or Tail Drop
4-priority
Scheduling
16-priority
Scheduling
per
SAP
RR
Rate
Fabric
per
SAP
CIR
(see Note 1)
Note 1: Aggregate shaper (CIR) for all the 4-priority unshaped SAPs.
Per SAP,
Per FC
Queuing
Per SAP,
2nd Tier
Aggregate
Shapers
Priority
Schedulers
Access Ingress
Aggregate Shaper &
Scheduler
Classification
nc
h1
be
nc
h1
be
Ethernet
SAPs
23369
Exp
In-Prof
BE
In-Prof
CoS-8
In-Prof
CoS-1
In-Prof
CoS-8
Out-Prof
CoS-1
Out-Prof
Exp
Out-Prof
BE
Out-Prof
Strict
Priority
Strict
Priority
CIR, PIR
CIR, PIR
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