Quality of Service (QoS): Managing Bandwidth More Effectively

Using QoS Classifiers To Configure Quality of Service for Outbound Traffic

Syntax: qos < udp-port tcp-port > < tcp or udp port number > dscp < codepoint >

Assigns a DSCP policy to packets having the specified TCP or UDP application port number and overwrites the DSCP in these packets with the assigned <codepoint> value. This policy includes an 802.1p priority and determines the packet’s queue in the outbound port to which it is sent. If the packet leaves the switch in a tagged VLAN, it carries the 802.1p priority with it to the next downstream device. (Default: No-override)

no qos < udp-port tcp-port > < tcp-udp port number >

Deletes the specified UDP or TCP port number as a QoS classifier.

show qos tcp-udp-port-priority

Displays a listing of all TCP and UDP QoS classifiers currently in the running-config file.

For example, suppose you wanted to assign these DSCP policies to the packets identified by the indicated UDP and TDP port applications:

Port Applications

DSCP Policies

 

DSCP

Priority

 

 

 

23-UDP

000111

7

80-TDP

000101

5

914-TDP

000010

1

1001-UDP

000010

1

 

 

 

1.Determine whether the DSCPs already have priority assignments, which could indicate use by existing applications. (Also, a DSCP must have a priority configured before you can assign any QoS classifiers to use it.)

The DSCPs for this example have not yet been assigned an 802.1p priority level.

Figure 15-4. Display the Current DSCP-Map Configuration

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