Quality of Service (QoS): Managing Bandwidth More Effectively

QoS Operating Notes and Restrictions

Maximum QoS Configuration Entries: The switches covered in this guide accept the maximum outbound priority and/or DSCP policy config­ uration entries of 128 rules per QoS feature.

Attempting to exceed the above limits generates the following message in the CLI:

Unable to add this QoS rule. Maximum number (entry-#) already reached.

All Switches—Not Supported: Use of an inbound 802.1p packet priority as a classifier for remapping a packet’s outbound priority to different 802.1p priority. For example, where inbound packets carry an 802.1p priority of 1, QoS cannot be configured use this priority as a classifier for changing the outbound priority to 0.

Not Supported: TCP/UDP QoS is not supported on fragmented packets. QoS is done by explicit hardware matching on packet information; in fragmented TCP/UDP packets the application port number is missing. As a result the behavior of fragmented packets is unpredictable.

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