Quality of Service (QoS): Managing Bandwidth More Effectively

Using QoS Classifiers to Configure Quality of Service for Outbound Traffic

 

3. Configure the DSCP policy by using qos dscp-mapto configure the priority

 

for each codepoint. (For details, refer to the example later in this section

 

and to “Differentiated Services Codepoint (DSCP) Mapping” on page

 

5-33.)

 

 

N o t e

A codepoint must have an 802.1p priority assignment (0 - 7) before you can

 

configure that codepoint as a criteria for prioritizing packets by source-port.

 

If a codepoint shows No-overridein the Priority column of the DSCP Policy

 

Table (show qos dscp-map), then you must assign a 0 - 7 priority before

 

proceeding.

 

4. Configure the switch to assign the DSCP policy to packets from the

 

 

specified source-port.

 

Syntax: qos dscp-map < codepoint > priority < 0 - 7 >

 

This command is optional if a priority has already been

 

assigned to the < codepoint >. The command creates a DSCP

 

policy by assigning an 802.1p priority to a specific DSCP.

 

When the switch applies this priority to a packet, the priority

 

determines the packet’s queue in the outbound port to which

 

it is sent. If the packet leaves the switch on a tagged port, it

 

carries the 802.1p priority with it to the next downstream

 

device. (Default: For most codepoints, No-override. See figure

 

5-9 on page 5-34 on page 5-34.)

 

Syntax: interface < port-list> qos dscp < codepoint >

 

Assigns a DSCP policy to packets from the specified source-

 

port(s), 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 on a

 

tagged port, it carries the 802.1p priority with it to the next

 

downstream device. (Default: No-override)

 

Syntax: no interface [e] < port-list> qos

 

Removes QoS classifier for the specified source-port(s).

 

Syntax: show qos source-port

 

Displays a listing of all source-port QoS classifiers currently

 

in the running-config file.

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