Cisco Systems 3750E Manual De Usuario

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Catalyst 3750-E and 3560-E Switch Software Configuration Guide
OL-9775-02
Chapter 36      Configuring QoS
Understanding QoS
In shared mode, the queues share the bandwidth among them according to the configured weights. The 
bandwidth is guaranteed at this level but not limited to it. For example, if a queue is empty and no longer 
requires a share of the link, the remaining queues can expand into the unused bandwidth and share it 
among them. With sharing, the ratio of the weights controls the frequency of dequeuing; the absolute 
values are meaningless.
For more information, see the 
, the 
, and the 
Queueing and Scheduling on Ingress Queues
 an
 show the queueing and scheduling flowcharts for ingress ports.
Figure 36-9
Queueing and Scheduling Flowchart for Ingress Ports on Catalyst 3750-E Switches
86693
Read QoS label
(DSCP or CoS value).
Determine ingress queue
number, buffer allocation,
and WTD thresholds.
Are thresholds
being exceeded?
Queue the packet. Service
the queue according to
the SRR weights.
Send packet to
the stack ring.
Drop packet.
Start
Yes
No