Quality of Service (QoS): Managing Bandwidth More Effectively Using QoS Classifiers to Configure Quality of Service for Outbound Traffic

QoS Source-Port Priority

QoS Classifier Precedence: 2

The QoS source-port option enables you to use a packet’s source-port on the switch as a QoS classifier. Where a particular source-port classifier has the highest precedence in the switch for traffic entering through that port, then traffic received from the port is marked with the source-port classifier’s configured priority level. Different source-port classifiers can have different priority levels.

Options for Assigning Priority on the Switch. Priority control options for packets from a specified source-port include:

802.1p priority

DSCP policy (Assigning a new DSCP and an associated 802.1p priority; inbound packets must be IPv4.)

(For operation when other QoS classifiers apply to the same traffic, refer to “Classifiers for Prioritizing Outbound Packets” on page 5-10.)

Options for Assigning Priority From a RADIUS Server. You can use a RADIUS server to impose a QoS source-port priority during an 802.1X port- access authentication session. Refer to the RADIUS chapter in the Access Security Guide for your switch.

Assigning a Priority Based on Source-Port

This option assigns a priority to all outbound packets having the specified source-port. You can configure this option by either specifying the source-port ahead of the qos command or moving to the port context for the port you want to configure for priority. (If you are configuring multiple source-ports with the same priority, you may find it easier to use the interface < port-list> command to go to the port context instead of individually configuring the priority for each port.)

Syntax: interface < port-list> qos priority < 0 - 7 >

Configures an 802.1p priority for packets entering the switch through the specified (source) ports. This priority determines the packet queue in the outbound port(s) to which traffic is sent. If a packet leaves the switch on a tagged port, it carries the 802.1p priority with it to the next downstream device. You can configure one QoS classifier for each source- port or group of source-ports. (Default: No-override)

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