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Cairo University

Faculty of Engineering

Electronics &Communication dpt.

4th year

Linux-basedImplementation Of a

Router

(B.Sc Graduation project)

Supervisor:

Prof. Dr. Khaled Foad El-Sayed.

Submitted by:

Ashraf Kamal Rahoma

Hazem Mohamed Sobhi Hassanein

Hossam El-Sayed Abd Allah

Tarek Amr Hamed

Zein El-Abidin Mohamed WALI

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Introduction to QoS:

Motivation:

QoS Terminology and Parameters:

Internet Protocol (IP).was designed to provide best-effort

service.

VoIP

FTP

QOS: Quality of Service (QoS) implies the ability to

differentiate traffic streams and to define a level of

performance for those traffic streams across a network. Whenheavily utilized networks are carrying various types of traffic

for different users, QoS is a mean of offering better service

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Parameters

1. Latency

the delay a flow experiences when passing through a device

2. Jitter

the latency variations

3. loss probability

bandwidth distribution and availability (throughput or

goodput)

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IntServ vs. DiffServ

IntServ overviewData path:

Per-flowclassification

Per-flowbuffermanagement.

Per-flowscheduling

Control path: Install and

maintainper-flow

state for dataand control

planes.

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RSVP Protocol

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RSVP Protocol

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RSVP Protocol

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RSVP Protocol

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IntServ vs. DiffServ

Each has its won points of strength

And weakness

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DiffServ Architecture

DiffServ Architectural Model

Differentiated Services Domain

DS Boundary Nodes and Interior Nodes:

DS Ingress Node and Egress Node:

Differentiated Services Region:

Traffic Classification and Conditioning:Classifiers:

Traffic Profiles:

Traffic Conditioners:

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Meters:

Markers:

Shapers:Droppers:

Location of Traffic Conditioners and MF Classifiers:

Within the Source Domain:At the Boundary of a DS Domain:

In non-DS-Capable Domains:

In Interior DS Nodes:

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ToS VS DSCP

Introduction

Type of service byte definition

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Type of service byte definition

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Table 2.1: IP precedence bits

Bits (0-2) IP-precedence definition

111 Network control

110 Internetwork control

101 CRITIC/ECP

100 Flash override

011 Flash

101 Immediate

001 Priority

000 routine

Table 2.2: ToS field values

Bits (3-6) ToS field definition

1000 Minimize delay

0100 Maximize throughput

0010 Maximize reliability

0001 Minimize monetary cost0000 Normal service

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Disadvantages of ToS

The IP-precedence scheme allows only specification of

relative priority of a packet. it has no provisions to specify

different drop precedence for packets of a certain priority.

The 3 bits restrict the number of possible priority classes to 8

The ToS mechanism is not powerful enough to allow an

application to quantify the level of service it desires.

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Differentiated services field definition

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Per Hop Behavior PHB

A per-hop behavior (PHB) is a description of the externally

observable forwarding behavior of a DS node applied to a

particular DS behavior aggregate (BA).

Different PHBs

Currently there are 4 standard different per

hop behaviors PHBs:

Default PHBClass-Selector PHB.

Assured Forwarding (AFny) PHB.

Expedited Forwarding (EF) PHB.

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ame DSCP (Hex) Description

Default PHB 000000 0x0h Best Effort (BE)

111000 0x38h Network Control

110000 0x30h Inter-netwrok Control101000 0x28h CRITIC/ECP

100000 0x20h Flash override

011000 0x18h Flash

101000 0x28h Immediate

Class-selectorHBs

xxx000

001000 0x8h Priority

xpeditedorwarding

F

101110 0xB8hLow-loss, low-latency,low-jitter and assured

bandwidth

010 0x28h Low dP

100 0x30h medium dP

AF1y

001

110 0x38h high dP

010 0x48h low dP

100 0x50h medium dPAF2y010

110 0x58h high dP

010 0x68h low dP

100 0x70h medium dPAF3y

011110 0x78h high dP

010 0x88h low dP

100 0x90h medium dP

ssured

orwardingF

AF4y

100110 0x98h high dP

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DiffServ Support under Linux

Linux Traffic Control Overview

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Linux Traffic ControllerSyntax:

tc [OPTIONS] OBJECT {COMMAND | help}

Where OBJECT: = {qdisc | class | filter}

OPTIONS: = {-s [tatistics] | -d [etails] | -r [aw]}

Queueing disciplines1.DSMARK2.CBQ3.TBF4.p/bFIFO5.PRIO6.RED7.GRED8.Ingress

Classes1.DSMARK2.CBQ

filters (or classifier)1.U322.TCINDEX3.ROUTE4.

FIREWALL

Police

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Implementation and Code

TC Implementation

Note: In this drawing only one AF class is shown for the simplicity of the

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Note: In this drawing only one AF class is shown for the simplicity of the

drawing, the other ones are just the same.

DSMARK

CBQ

pFIFO:Low queuing delay (latency).

Well defined minimum departure rate, i.e. independent of

the other traffic at the node.

No burst. (policing).4 CBQ:

Four AF classes with different fractions of the bandwidth

allocated for each.

In each one we have three dropping precedences (RED)

Bandwidth assurance,RED:

No bandwidth guarantee.

No quality of service: No policing filters, no

shaping.

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Traffic Classes

Variables:

Setting Functions:

Constructor.Destructor

Set Device

Set Network

Set Rates

Set PHBs

Set Police

Set ToS

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Infra-structure Functions:

t_start( ) t_reset( )

Make_phb( )

make_EF( )

make_AF( )

make_BE( )

make_Subfilter( )

make_marker( )

Filtering Functions:

Make Filter

Get Command

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Software implementation

Architecture Overview.

Graphical User Interface (GUI).

System programming.

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using C++ Classes

Architecture Overview

To ensure encapsulation & independence

To control the communication & error

tracing

To give the ability to change or

update any specific parts.

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using C++ Classes

Architecture Overview

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Detailed view

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Communication between Classes

TrafficClass

l nc t h

t l ic in

Apply_phb()Set_device()

Set_network()

Set_Rates()

Apply_advanced() Set_phb()Set_policing()

Set_tos()

Apply_filter() make_filter()

DiffServClass

l nc t h

t l ic in

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GUI tabs

PHB configuration tab

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Advanced PHB

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Filter Setup Tab

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Summary view Tab

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TC Experts Tab

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4.4 Testing:

Description PC1 DiffServ Router PC2

Platform Linux Linux Windows XP

Speed PIII 1000 MHZ PIII 850 MHZ PIII 600 MHZ

Running s/w Traffic Generator( TG)

DiffServ S/WTraffic Monitoring(CommView)

eth0Ethernetcards

eth0eth1

eth0

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4.5 Testing procedure

We have performed testing on 3 basic levels:

1. Marking: Testing if packets were marked according to

specified classification.

2. ToS: Testing if the classification according to ToS and

monitoring packets flow were mapped to the required

PHB

3. PHBs Implementation: Monitoring different ratesassigned to each class

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Than You !