Classifying Traffic On A Per-Port Per-Vlan Basis By Using Class Maps - Cisco Catalyst 3550 series Software Configuration Manual

Chapter 29 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
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

Classifying Traffic on a Per-Port Per-VLAN Basis by Using Class Maps

You use the class-map global configuration command to name and to isolate a specific traffic flow (or
class) from all other traffic. To further classify the traffic flow, the class map defines the matching criteria
to use.
To define packet classification on a per-port per-VLAN basis, follow these guidelines:
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When you use the match vlan vlan-list class-map configuration command, you can enter up to 30 VLAN
Note
IDs. When you enter a range of VLANs, such as 10-15, the VLAN range is counted as two VLAN IDs.
78-11194-09
You must use the match-all keyword with the class-map global configuration command.
Per-port per-VLAN classification is a per-port feature and does not work on redundant links. It is
supported only on an ingress port configured as a trunk or as a static-access port.
The class map must have two match commands in this order: one match vlan vlan-list class-map
configuration command and one match class-map class-map-name class-map configuration
command. The class map specified in the match class-map class-map-name command must be
predefined and cannot contain the match vlan vlan-list and the match class-map class-map-name
commands.
You cannot configure both port-based classification and VLAN-based classification at the same
time. When you configure the match vlan vlan-list command, the class map becomes per-port
per-VLAN based. If you configure a policy map that contains both port-based and VLAN-based
class maps, the switch rejects the policy map when you attach it to an interface.
With per-port per-VLAN classification, unmatched VLANs are treated similarly to the default class,
which means that the unmatched VLANs share the remaining bandwidth from those used by the
matched VLAN classes. You cannot modify this default-class behavior. If necessary, you can use
VLAN map filters to block these VLANs.
Within a policy map, when you use the match vlan vlan-list command, all other class maps must
use the match vlan vlan-list command.
If you want to modify the VLAN list, first remove the previous configuration in the class map by
using the no match vlan vlan-list command and the no match class-map class-map-name
command. Then reconfigure the class map, and specify the new VLAN list. If the policy map is
attached to an interface and you modify the class map by using any other method, the policy map
detaches from the interface.
Catalyst 3550 Multilayer Switch Software Configuration Guide
Configuring Standard QoS
29-41