Related Topics
Queueing and Scheduling on Ingress Queues, on page 556
Examples: Configuring Ingress Queue Characteristics, on page 639
SRR Shaping and Sharing, on page 555
Configuring Egress Queue Characteristics
Depending on the complexity of your network and your QoS solution, you might need to perform all of the
tasks in the following modules. You need to make decisions about these characteristics:
•
Which packets are mapped by DSCP or CoS value to each queue and threshold ID?
•
What drop percentage thresholds apply to the queue-set (four egress queues per port), and how much
reserved and maximum memory is needed for the traffic type?
•
How much of the fixed buffer space is allocated to the queue-set?
•
Does the bandwidth of the port need to be rate limited?
•
How often should the egress queues be serviced and which technique (shaped, shared, or both) should
be used?
Related Topics
Shaped or Shared Mode, on page 562
Configuration Guidelines
Follow these guidelines when the expedite queue is enabled or the egress queues are serviced based on their
SRR weights:
•
If the egress expedite queue is enabled, it overrides the SRR shaped and shared weights for queue 1.
•
If the egress expedite queue is disabled and the SRR shaped and shared weights are configured, the
shaped mode overrides the shared mode for queue 1, and SRR services this queue in shaped mode.
•
If the egress expedite queue is disabled and the SRR shaped weights are not configured, SRR services
this queue in shared mode.
Allocating Buffer Space to and Setting WTD Thresholds for an Egress Queue-Set
You can guarantee the availability of buffers, set WTD thresholds, and configure the maximum allocation for
a queue-set by using the mls qos queue-set output qset-id threshold queue-id drop-threshold1 drop-threshold2
reserved-threshold maximum-threshold global configuration command.
Each threshold value is a percentage of the queue’s allocated buffers, which you specify by using the mls qos
queue-set output qset-id buffers allocation1 ... allocation4 global configuration command. The queues use
WTD to support distinct drop percentages for different traffic classes.
Consolidated Platform Configuration Guide, Cisco IOS Release 15.2(4)E (Catalyst 2960-X Switches)
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How to Configure QoS
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