33-4
Cisco ME 3400 Ethernet Access Switch Software Configuration Guide
OL-9639-07
Chapter 33 Configuring QoS
Understanding QoS
class1 interface configuration command attaches all the characteristics of the traffic policy named class1
to the specified interface. All packets leaving the specified interface are evaluated according to the
criteria specified in the traffic policy named class1.
Note If you enter the no policy-map configuration command or the no policy-map policy-map-name global
configuration command to delete a policy map that is attached to an interface, a warning message
appears that lists any interfaces from which the policy map is being detached. The policy map is then
detached and deleted. For example:
Warning: Detaching Policy test1 from Interface GigabitEthernet0/1
Input and Output Policies
Policy maps are either input policy maps or output policy maps, attached to packets as they enter or leave
the switch by service policies applied to interfaces. Input policy maps perform policing and marking on
received traffic. Policed packets can be dropped or reduced in priority (marked down) if they exceed the
maximum permitted rates. Output policy maps perform scheduling and queuing on traffic as it leaves the
switch.
Input policies and output policies have the same basic structure; the difference is in the characteristics
that they regulate.
Figure 33-2 shows the relationship of input and output policies.
You can configure a maximum of 256 policy maps.
You can apply one input policy map and one output policy map to an interface.
When CPU protection is enabled (the default), you can configure 45 ingress policers per port. If you
disable CPU protection by entering the no policer cpu uni all global configuration command and
reloading the switch, you can configure a maximum of 63 policers per port (62 on every 4th port) for
user-defined classes and one for class-default. You can enter the show policer cpu uni-eni {drop | rate}
privileged EXEC command to see if CPU protection is enabled.
Figure 33-2 Input and Output Policy Relationship
Input Policy Maps
Input policy map classification criteria include matching a CoS, a DSCP, or an IP precedence value or
matching an access control list (ACL) or VLAN ID (for per-port, per-VLAN QoS). Input policy maps
can have any of these actions:
• Setting or marking a CoS, a DSCP, an IP precedence, or QoS group value
• Individual policing
• Aggregate policing
Ingress
port
Apply
input
policy
Apply
output
policy
141150
Switching
and
forwarding
Egress
port
Apply
output
policy
Apply
input
policy
To Next Page
Loading...
