Quality of Service (QoS): Managing Bandwidth More Effectively

Using QoS Classifiers To Configure QoS for Outbound Traffic

vlan-priority

Displays the current VLAN priority configuration.

Refer to figure 6-23 on page 6-48.

port-priority

Displays the current source-port priority configuration. Refer to figure 6-28 on page 6-53.

No Override

By default, the IP ToS, VLAN-ID, and (source) port show outputs automatically list No-overridefor priority options that have not been configured. This means that if you do not configure a priority for a specific option, QoS does not prioritize packets to which that option applies, resulting in the No override state. In this case, IP packets received through a VLAN-tagged port receive whatever 802.1p priority they carry in the 802.1Q tag in the packet’s header. VLAN-tagged packets received through an untagged port are handled in the switch with “normal” priority. For example, figure 6-5below shows a qos VLAN priority output in a switch where nondefault priorities exist for VLANs 22 and 33, while VLAN 1 remains in the default configuration.

This output shows that VLAN 1 is in the default state, while VLANs 22 and 33 have been configured for 802.1p and DSCP Policy priorities respectively.

Figure 6-5. Example of the Show QoS Output for VLAN Priority

QoS UDP/TCP Priority

QoS Classifier Precedence: 1

When you use UDP or TCP and a layer 4 Application port number as a QoS classifier, traffic carrying the specified UDP/TCP port number(s) is marked with the UDP/TCP classifier’s configured priority level, without regard for any other QoS classifiers in the switch.

The UDP/TCP QoS option uses two rules per entry on all ports in the switch.

N o t e

UDP/TCP Qos applications do not support IPV4 packets with IP options.

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