Dell PowerConnect 5548 User Guide - Page 668

QoS Advanced Mode This section describes QoS Advanced mode. It contains the following topics: • Advanced Mode Overview • Workflow to Configure Advanced QoS Mode • DSCP Mapping • Class Mapping • QoS Policers • Policy Binding Advanced Mode Overview In Advanced mode, the switch uses policies to support per-flow QoS. A policy and its components have the following characteristics and relationships: • A policy contains one or more class maps. • A class map defines a flow with one or more associated ACLs. Packets that match the ACL rules (ACEs) in a class map with Permit (forward) action, belong to the same flow, and are subject to the same quality of service action. A policy can contain one or more flows, each with a user-defined QoS action. • The QoS of a class map (flow) may be enforced by the associated policer. There are two type of policers, as described in "Defining Class Mapping Using CLI Commands" on page 674. • Per-flow QoS actions are applied to flows by binding the policy maps to the desired ports. A policy map and its class maps can be bound to one or more ports, but each port is bound with, at the most, one policy map. The following points should be considered: • An ACL can be configured to one or more class maps, regardless of policies. • A class map can belong to only one policy map. • When a class map, using a single policer, is bound to multiple ports, each port has its own instance of the policer. Each instance applies the QoS actions on the class map (flow) at a port independent of each other. 668 Dell PowerConnect 55xx Systems User Guide