Quick Reference Guide

PowerConnect B-Series TI24X Configuration Guide 187

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Egress buffer thresholds for QoS priorities

NOTES:

• The terms QoS priority and traffic class are used interchangeably in this section and

mean the same thing.

• Buffer threshold level-3 to maximum does not change the buffering behavior of the

device.

The PowerConnect switch uses egress buffer threshold levels to dynamically adjust each port

egress queue (outbound transmit queue) based on QoS priority (traffic class) and jumbo frame

support. When the egress buffer queue is full, any new packets destined for the egress queue will

be dropped.

The following egress buffer thresholds can be adjusted by an administrator:

• Egress Buffer Threshold for all Traffic Classes for a port – When this is configured, the

specified egress buffer threshold will be applied to all traffic classes (0 – 7) on a port.

• Egress Buffer Threshold for a given Traffic Class for a port – When this is configured, the

specified egress buffer threshold will be applied to a specific traffic class (0 – 7) on a port.

The egress buffer thresholds can be modified to various levels. The default settings are described

in the section “Default settings for egress buffer thresholds” on page 188. Note that based on the

egress buffer threshold assigned, the system will dynamically control the egress CoS queue size for

a port based on the current buffer usage information from the system.

Figure 32 shows the egress buffer thresholds.