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RCA THOMSON SpeedTouchTM (Wireless) Business DSL Router 3.3 Classification and conditioning principles

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Chapter 3

Basic QoS Concepts

E-NIT-CTC-20041213-0013v0.5

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3.3 Classification and conditioning principles

Introduction Packets go through a number of phases as they transit the network: classification,

marking, shaping, policing and queuing. These phases can occur a number of times

at each QoS-aware router in the path of the packet.

For example, a host might mark outgoing traffic as "best effort", "scavenger",

"discard at edge" or "discard at paid link". The hosts router might then police the

host's traffic to ensure that these are the only markings applied to traffic, and remark

invalidly marked packets as "best effort".

The traffic conditioners are usually located in DiffServ boundary nodes, so interior

nodes do not need to perform any traffic conditioning.

Traffic classification A packet is classified as belonging to a "class of service". This classification is done

by the boundary nodes.

The BA classifier classifies the packets by the DSCP. Classification is based on the

value of combination of one or more IP header fields, such as source and destination

addresses, source and destination ports, protocol ID and other information like

incoming interface.

For example, we might classify data from a VoIP gateway as being "voice" traffic.

Traffic conditioning Traffic conditioning includes metering, policing, shaping and possibly re-marking to

ensure that the traffic stream entering the DiffServ domain conforms to the rules

specified in the SLS. The traffic conditioning policies are negotiated between the

networks and vary from simple re-marking to complex policing and shaping

operations.

The traffic conditioner includes meter, marker, shaper and dropper. The packets are

directed from the traffic classifier to the logical instance of traffic conditioner.

The figure above shows that the packets travel from the classifier either to the meter

or to the marker.

The meter measures the rate at which packets of one BA pass the meter. It is used

to measure the traffic stream against the traffic profile.

The marker adds the packet to the appropriate BA according to the DSCP. The DSCP

may be changed by the marker, i.e. re-marked.

Shapers shape the packet stream to fit in the used traffic profile. The shaper may

also act as a dropper by dropping packets to fit the stream into the profile.

packet

stream shaper/dropper

classifier

meter

marker

Contents

Main Page Page Page Contents Contents 4 6 Meters, queues and IPQoS......................................... 59 7 Scenario 1: Residential user.......................................85 Page Page About this IPQoS Configuration Guide About this IPQoS Configuration Guide ! Page Chapter 1 1 Document scope Page 2Introduction 2.1 What is Quality of Service? Definition Misunderstandings ! Page 2.2 Relative versus Guaranteed QoS Types of QoS 3 Basic QoS Concepts 3.1 Precedence and TOS Introduction First generation Precedence values Second generation 3.2 Differentiated Services Differentiated Services domain 3.3 Classification and conditioning principles Introduction classifier Traffic classification Traffic conditioning Page 3.4 Differentiated Services Code Point (DSCP) Introduction Per Hop Behaviour Standardized PHBs Page Assured Forwarding (AF) PHB Group: 4 IP QoS Framework Overview 4.1 Main Framework Components Graphical overview QoS Components 4.2 Resource Management Mapping to internal class 5 Packet Classification and Labelling 5.1 Classification Introduction Terminology 5.1.1 Order of classification rules Introduction Routing classification Sub-chains ! Page 5.2 Labels Introduction CLI Command groups ! Label command group Adding a label Label parameters Debug command group 5.2.1 Label parameters explained Introduction Classification Defclass Page Page 5.2.2 Using TOS, DSCP or Precedence Introduction Precedence TOSmarking TOS DSCP 5.2.3 Forwarding parameters. Introduction TTLoverwrite TTL Modify the label parameters Page 5.3 Rules 5.3.1 Rules parameters explained Introduction Srcintf Chain Index Srcip Dstip Serv Page The flush command 5.3.2 Rule debug commands Introduction Traceconfig Traceconfig result Stats 5.4 Chains Page 5.4.1 Define a relation between chains 5.5 Expressions Page Bridgeport Addr Precedence Tos Dscp ! Srcportend Dstport Icmptype Dstportend Page Page 6 Meters, queues and IPQoS 6.1 Meters and queues 6.2 The IPQoS command group Overview IPQoS command group EF command group meter command group Page Page Page MTU explained. EF stats command EF list command Line Speed 6.4 Meter command group Introduction Adding a meter 6.4.1 Meter config command Meter parameters meter config Label Meter config parameters explained Name Intf Droprate Markrate Burst Page Dscp Precedence Class Classification Meter delete command Meter list command Meter start command Meter stop command Meter flush command Meter stats command 6.4.2 Packet flow Illustration Classification Metering 6.5 Queue command group Introduction Queue config command 6.5.1 Queue config parameters explained Dest Ecnmarking Queue Propagate Data ACK1Data DataACK2 Example Maxpackets Respackets Maxbytes Resbytes Hold Markprob Queue list command Queue stats command Queue clear command 6.6 IPQoS Command group Introduction ipqos config command 6.6.1 Ipqos config parameters explained Introduction Dest Discard State ! Priority Realtimerate Burstsize Weight Maxpackets Maxbytes Ipqos list command 7 Scenario 1: Residential user. 7.1 Configuring labels and rules for VoIP. Introduction The web interface Labels Rules Expressions Page 7.2 Configuring labels and rules for DSCP. Introduction Labels Rules Expressions 7.3 Configuring labels and rules for Interactive traffic. Introduction Labels Page Expressions Page Page 8 Scenario 2: Business user with TOS marking. ! 8.1 Labels Page Page Page 8.2 Rules. Page Page Page Page Page Page Page Page 8.3 IPQoS per PVC Page Page Chapter 9 9 Scenario 3: Metering Page Reference List Reference List Page Abreviation List Abreviation List