CANOGA PERKINS CanogaOS Configuration Guide - Manual (Page 269)

CanogaOS Configuration Guide
Proprietary & Confidential Canoga Perkins Metro Ethernet Switches Page 269 of 350
• Weighted Deficit Round Robin (WDRR), in which each queue is assigned a weight to control
the number of packets relatively sent from each queue.
Class Map
A class map names and isolates specific traffic from other traffic. The class map defines the
criteria used to match against a specific traffic flow to further classify it. The criteria can match
several access groups defined by the ACL.
If there is more than one type of traffic to be classified, another class map can be created under a
different name. After a packet is matched against the class-map criteria, it is further classified
using a policy map.
Policy Map
A policy map specifies on which traffic class to act. This can be implemented as follows:
• Set a specific priority and color in the traffic class.
• Set a specific trust policy to map priority and color.
• Specify the traffic bandwidth limitations for each matched traffic class (policer) and the action
to take (marking) when the traffic is out of profile.
Policy maps have the following attributes:
• A policy map can contain multiple class statements, each with different match criteria and
action.
• A separate policy-map class can exist for each type of traffic received through an interface.
• There can be only one policy map per interface per direction. The same policy map can be
applied to multiple interfaces and directions.
• Before a policy map can be effective, it must be attached to an interface.
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.