Cisco IE 4000, Руководство по настройке программного обеспечения

Страница: 578 / 1066

574
Configuring QoS
Understanding QoS
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 77 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
Only input policies provide matching on access groups or VLAN IDs, and only output policies provide matching on QoS
groups. You can assign a QoS group number in an input policy and match it in the output policy. The class
class-default
is used in a policy map for any traffic that does not explicitly match any other class in the policy map. Input policy maps
do not support queuing and scheduling keywords, such as
bandwidth , queue-limit , priority , and shape average .
An input policy map can have a maximum of 64 classes plus class-default . You can configure a maximum of 64 classes
in an input policy.
Output Policy Maps
Output policy map classification criteria include matching a CoS, a DSCP, an IP precedence, or a QoS group value. Output
policy maps can have any of these actions:

Queuing ( queue-limit )

Scheduling ( bandwidth , priority , and shape average )
Output policy maps do not support matching of access groups. You can use QoS groups as an alternative by matching
the appropriate access group in the input policy map and setting a QoS group. In the output policy map, you can then
match the QoS group. See
Classification Based on QoS Groups, page 580 for more information.
Output policies do not support marking or policing (except in the case of priority with policing). There is no egress packet
marking on the switch (no
set command in an output policy).
The class class-default is used in a policy map for any traffic that does not explicitly match any other class in the policy
map. There can be a maximum of four classes in the output policy map (including class-default) because egress ports
have a maximum of four queues.
An output policy map attached to an egress port can match only the packets that have already been matched by an input
policy map attached to the ingress port for the packets. You can attach an output policy map to any or all ports on the
switch. The switch supports configuration and attachment of a unique output policy map for each port. However, these
Ingress
port
Apply
input
policy
Apply
output
policy
141150
Switching
and
forwarding
Egress
port
Apply
output
policy
Apply
input
policy