How Does Diffserv Functionality Vary Based On The Role Of The Switch; What Are The Elements Of Diffserv Configuration - Dell PowerEdge M420 Configuration Manual

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