Restrictions For Applying A Qos Service Policy - Cisco Catalyst 4500 series Administration Manual

Configuring QoS on a Standalone Supervisor Engine 6-E/6L-E or Supervisor Engine 7-E/7L-E/8-E

Restrictions for Applying a QoS Service Policy

Traffic marking can be configured on an interface, a VLAN, or a port and VLAN. An interface can be a
Layer 2 access port, a Layer 2 switch trunk, a Layer 3 routed port, or an EtherChannel. A policy is
attached to a VLAN using vlan configuration mode.
Attaching QoS service policy to VLANs and EtherChannel is described in the
section on page
Classification
The supervisor engine supports classification of Layer 2, IP, IPv6 packets, and ARP packets marking
performed on input can be matched in the output direction. The previous table lists the full set of
capabilities. By default, the switch also supports classification resources sharing. Similarly, when the
same policy is attached to a port or a VLAN or on per-port per-vlan targets, ACL entries are shared
though QoS actions are unique on each target.
For example:
Policy Map p1
If policy-map p1 is applied to interfaces Gig 1/1 and Gig 1/2, 1 CAM entry is used (one ACE that
matches IP packets), but 2 policers are allocated (one per target). So, all IP packets with dscp 50 are
policed to 1 mbps on interface Gig 1/1 and packets on interface Gig 1/2 are policed to 1 mbps.
With Cisco IOS Release 12.2(46)SG, you can issue the match protocol arp command. For details, see
Note
the Catalyst 4500 Series Switch Cisco IOS Command Reference.
Classification Statistics
The supervisor engine supports only packet based classification statistics and TCAM resource sharing.
When a policy-map is applied on multiple targets, the command show policy-map interface displays
the aggregate classification statistics, not those specific to an interface.
Note To obtain per interface policy-map stats, you should configure a unique policy-map name on each
interface.
When a policy-map is attached to a port-channel member ports, classification statistics are not displayed.
Configuring a Policy Map
You can attach only one policy map to an interface. Policy maps can contain one or more policy-map
classes, each with different match criteria and actions.
Configure a separate policy-map class in the policy map for each type of traffic that an interface receives.
Put all commands for each type of traffic in the same policy-map class. QoS does not attempt to apply
commands from more than one policy-map class to matched traffic.
Software Configuration Guide—Release IOS XE 3.6.0E and IOS 15.2(2)E
42-50
42-73.
class-map c1
match ip dscp 50
class c1
police rate 1 m burst 200000
Chapter 42 Configuring Quality of Service
"Policy Associations"
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