CANOGA PERKINS 9175 Configuration Guide - Manual (Page 211)

CanogaOS Configuration Guide
31-5
Mapping Tables
During QoS processing, the switch represents the priority of all traffic (including non-IP
traffic) with an internal priority value:
• During classification, QoS uses configurable mapping tables to derive the internal
priority (a 6-bit value) from received CoS, EXP(3-bit), DSCP or IP precedence
(3-bit) values. These maps include the CoS-to-priority-color map,
EXP-to-priority-color map, DSCP-to-priority-color map and the IP-precedence-to-
priority-color map.
• During policing, QoS can assign another priority and color to an IP or non-IP
packet (if the packet matches the class-map). This configurable map is called the
policed-priority-color map.
• Before the traffic reaches the scheduling stage, and replace CoS or DSCP is set,
QoS uses the configurable priority-color-to-CoS or priority-color-to-DSCP map to
derive a CoS or DSCP value from the internal priority color.
31.3 Configuration Guidelines
The following provides information to consider before configuring QoS:
• QoS policing cannot be configured on Linkagg interface.
• Traffic can be only classified per ingress port.
• There can be multiple ACLs per class map. An ACL can have multiple access
control entries that match fields against the packet contents.
• Policing cannot be done at the switch virtual interface level.
31.4 Configuration
The following subsections provide examples of how to enable and configure QoS.
Commands are indicated in bold Courier type. Parameters are indicated in plain Courier
type. Additional information is indicated in Arial type.
31.4.1 Enable QoS
By default, QoS is disabled on the switch, which means that the switch offers best-effort
service to each packet regardless of the packet contents or size. All the packets map to
egress queue 0 with both tail-drop thresholds set to 100 percent of the total queue size.
When the buffer is full, packets are dropped.
To enable QoS, enter the following commands from Privileged Exec mode.
• configure
terminal.
• qos
enable
Note: The no qos enable command disables QoS.
The following example shows enabling QoS.
DUT# configure terminal
DUT(config)# qos enable
31.4.2 Configure egress queue
Tail Drop