Dell PowerEdge M420 Dell PowerConnect M8024-k User's Configuration Guide - Page 1098

How Does DiffServ Functionality Vary Based on the Role of the Switch? How you configure DiffServ support in PowerConnect M6220/M6348/M8024/M8024-k switch software varies depending on the role of the switch in your network: • Edge device: An edge device handles ingress traffic, flowing towards the core of the network, and egress traffic, flowing away from the core. An edge device segregates inbound traffic into a small set of traffic classes, and is responsible for determining a packet's classification. Classification is primarily based on the contents of the Layer 3 and Layer 4 headers, and is recorded in the Differentiated Services Code Point (DSCP) added to a packet's IP header. • Interior node: A switch in the core of the network is responsible for forwarding packets, rather than for classifying them. It decodes the DSCP in an incoming packet, and provides buffering and forwarding services using the appropriate queue management algorithms. Before configuring DiffServ on PowerConnect M6220, M6348, M8024, and M8024-k switches, you must determine the QoS requirements for the network as a whole. The requirements are expressed in terms of rules, which are used to classify inbound or outbound traffic on a particular interface. What Are the Elements of DiffServ Configuration? During configuration, you define DiffServ rules in terms of classes, policies, and services: • Class: A class consists of a set of rules that identify which packets belong to the class. Inbound traffic is separated into traffic classes based on Layer 2, Layer 3, and Layer 4 header data. The class type All is supported; this specifies that every match criterion defined for the class must be true for a match to occur. • Policy: A policy defines the QoS attributes for one or more traffic classes. An attribute identifies the action taken when a packet matches a class rule. An example of an attribute is to mark a packet. The switch supports the ability to assign traffic classes to output CoS queues, and to mirror incoming packets in a traffic stream to a specific egress interface (physical port or LAG). PowerConnect M6220/M6348/M8024/M8024-k switch software supports the Traffic Conditioning Policy type which is associated with an inbound 1098 Configuring Differentiated Services