20-32
Catalyst 3550 Multilayer Switch Software Configuration Guide
78-11194-03
Chapter 20 Configuring QoS
Configuring QoS
This example shows how to create a class map called class2, which matches incoming traffic with DSCP
values of 10, 11, and 12.
Switch(config)# class-map class2
Switch(config-cmap)# match ip dscp 10 11 12
Switch(config-cmap)# end
Switch#
This example shows how to create a class map called class3, which matches incoming traffic with
IP-precedence values of 5, 6, and 7:
Switch(config)# class-map class3
Switch(config-cmap)# match ip precedence 5 6 7
Switch(config-cmap)# end
Switch#
Classifying, Policing, and Marking Traffic by Using Policy Maps
A policy map specifies which traffic class to act on. Actions can include trusting the CoS, DSCP, or IP
precedence values in the traffic class; setting a specific DSCP or IP precedence value in the traffic class;
and specifying the traffic bandwidth limitations for each matched traffic class (policer) and the action to
take when the traffic is out of profile (marking).
A policy map also has these characteristics:
•
A policy map can contain multiple class statements, each with different match criteria and policers.
•
A separate policy-map class can exist for each type of traffic received through an interface.
•
A policy-map trust state supersedes an interface trust state.
You can attach only one policy map per interface per direction.
Beginning in privileged EXEC mode, follow these steps to create a policy map:
Command
Purpose
Step 1
configure terminal
Enter global configuration mode.
Step 2
mls qos
Enable QoS on the switch.
Step 3
access-list access-list-number {deny |
permit} source [source-wildcard]
or
access-list access-list-number {deny |
permit} protocol source [source-wildcard]
destination [destination-wildcard]
or
mac access-list extended access-list name
{permit | deny} {source-MAC-addr mask |
any | host} {destination-MAC-addr mask |
any | host} [ethertype]
Create an IP standard or extended ACL for IP traffic or a Layer 2 MAC
ACL for non-IP traffic, repeating the command as many times as
necessary.
For more information, see the
“Classifying Traffic by Using ACLs”
section on page 20-27
.
Note
When creating an access list, remember that, by default, the end
of the access list contains an implicit deny statement for
everything if it did not find a match before reaching the end.
