Transcript QoS Terminology and Parameters

Cairo University
Faculty of Engineering
Electronics &Communication dpt.
4th year
Linux-based
Implementation Of a
Router
Supervisor:
Prof. Dr. Khaled Foad El-Sayed.
Submitted by:
Ashraf Kamal Rahoma
(B.Sc Graduation project)
Hazem Mohamed Sobhi Hassanein
Hossam El-Sayed Abd Allah
Tarek Amr Hamed
Zein El-Abidin Mohamed WALI
Apr-16
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Introduction to QoS:
Motivation:
Internet Protocol (IP).was designed to provide best-effort
service.
•
VoIP
•
FTP
QoS Terminology and Parameters:
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. When
heavily 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 overview
Data path:
 Per-flow
classification
 Per-flow
buffer
management
.
 Per-flow
scheduling
Control path:
 Install and
maintain
per-flow
state for data
and 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)
111
110
101
100
011
101
001
000
IP-precedence definition
Network control
Internetwork control
CRITIC/ECP
Flash override
Flash
Immediate
Priority
routine
Table 2.2: ToS field values
Bits (3-6)
1000
0100
0010
0001
0000
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ToS field definition
Minimize delay
Maximize throughput
Maximize reliability
Minimize monetary cost
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 PHB’s
Currently there are 4 standard different per
hop behaviors PHB’s:
Default PHB
Class-Selector PHB.
Assured Forwarding (AFny) PHB.
Expedited Forwarding (EF) PHB.
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Name
DSCP
(Hex)
Description
Default PHB
000000
0x0h
Best Effort (BE)
111000
110000
101000
100000
011000
101000
001000
0x38h
0x30h
0x28h
0x20h
0x18h
0x28h
0x8h
101110
0xB8h
Network Control
Inter-netwrok Control
CRITIC/ECP
Flash override
Flash
Immediate
Priority
Low-loss,
low-latency,
low-jitter and assured
bandwidth
Low dP
medium dP
high dP
low dP
medium dP
high dP
low dP
medium dP
high dP
low dP
medium dP
high dP
Class-selector
PHBs
’xxx000’
Expedited
Forwarding
EF
AF1y
001
Assured
Forwarding
AF
AF2y
010
AF3y
011
AF4y
100
Apr-16
010
100
110
010
100
110
010
100
110
010
100
110
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0x28h
0x30h
0x38h
0x48h
0x50h
0x58h
0x68h
0x70h
0x78h
0x88h
0x90h
0x98h
DiffServ Support under Linux
Linux Traffic Control Overview
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Linux Traffic Controller
Syntax:
tc [OPTIONS] OBJECT {COMMAND | help}
Where OBJECT: = {qdisc | class | filter}
OPTIONS: = {-s [tatistics] | -d [etails] | -r [aw]}
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 Queueing disciplines
1. DSMARK
2. CBQ
3. TBF
4. p/bFIFO
5. PRIO
6. RED
7. GRED
8. Ingress
 Classes
1. DSMARK
2. CBQ
 filters (or classifier)
1. U32
2. TCINDEX
3. ROUTE
4. FIREWALL
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 Police
Implementation and Code
TC Implementation
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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 precedence’s (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 PHB’s
Set Police
Set ToS
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Infra-structure Functions:
t_reset( )
t_start( )
make_marker( )
Make_phb( )
make_BE( )
make_EF( )
make_Subfilter( )
make_AF( )
Filtering Functions:
Make Filter
Get Command
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Software implementation
Architecture Overview.
Graphical User Interface (GUI).
System programming.
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Architecture Overview
using C++ Classes
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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Architecture Overview
using C++ Classes
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Detailed view
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Communication between Classes
Apply_phb()
DiffServ
Class
A pp ly _advanced()
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Set_device()
Set_network()
Set_Rates()
Apply_advanced()
Set_phb()
Set_policing()
Set_tos()
Apply_filter()
make_filter()
Set_phb ()
Set_ polici ng()
Traffic
Class
A pp ly _advanced()
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Set_phb ()
Set_ polici ng()
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
Speed
PIII –1000 MHZ
Running s/w Traffic Generator
( TG)
Ethernet
eth0
cards
Linux
PIII –850 MHZ
Windows XP
PIII –600 MHZ
Traffic Monitoring
(CommView)
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DiffServ S/W
eth0
eth1
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eth0
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. PHB’s Implementation: Monitoring different rates
assigned to each class
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Than You !
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