1 Chapter 2. Networks and and communication protocols INE4481 DISTRIBUTED DATABASES & CLIENT-SERVER ARCHITECTURES
Jan 05, 2016
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Chapter 2.Networks and and
communication protocols
INE4481 DISTRIBUTED DATABASES & CLIENT-SERVER ARCHITECTURES
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CONTENT
1. HISTORY
o Centralized Processing (1960 -
1970)
o Networks (1970 - 1980)
o Inter-networks (1980 - 1990)
o Internet: Network of networks
2. RECALLS ON NETWORK SYSTEMS
3. OSI vs TCP/IP
o THE SEVEN OSI LAYERS
o OSI’s PROTOCOLS DATA
TRANSMISSION
o TCP/IP MODEL
o TCP/IP NETWORKS SERVICES
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4. WHAT ABOUT NETWORKS?
o INTERCONNECTED NETWORKS
o LOCAL NETWORKS
STANDARDS
o IRQ (Interrupted Request)
AND ERRORS PROCESSING
o SEQUENCE NUMBERS
o FLOW CONTROL MECHANISMS
o THE NETWORK LAYER
o SWITCHING TECHNIQUES
o ROUTING
5. TCP/IP
o TCP/IP PROTOCOLS
o THE IP PROTOCOL
o IP ADRESSES
o THE TCP PROTOCOL
o THE UDP PROTCOL
o SERVICES DEDICATED PORTS
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NETWORKS HISTORY
oThe steps towards Internet :
oCentralized Processing (1960 - 1970)
oNetworks (1970 - 1980)
oInter-networks (1980 - 1990)
oInternet: Network of networks
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Centralized Processing (1960 - 1970)
Mainframe Host A Mini-computer
Host B
terminal
Remote terminal R.V.A.
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Networks (1970 - 1980)
Token Ring
Ethernet
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Inter-networks (1980 - 1990)
Token Ring
Ethernet
FDDI
Serial WAN Connexion
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Internet: Network of networks
ATMSwitcher
Router
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RECALLS ON NETWORK SYSTEMS
The reference model for open systems interconnection is OSI.oUsed to structured communication software components.oCreated by the International Standard Organisation ISO. oIntended to enable interoperablity between protocols and between networks applications.
OSI model:Machine A Machine B
Layer N+1layer N+1 Protocol
layer N Protocol
Layer N+1/N Interface
Layer N+1
Layer N Layer N
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THE SEVEN OSI LAYERS
Protocole d'application : FTP, SMTP, HTTP, SIP
Session protocol: TCP
Presentation protocol: XDR, CORBA
Application
Physical
Session
Présentation
Transport
Network
Bit
Frame
Paquet
Message
Message
Message
Sub-network Device B
Physical
Network
Physical
Network
Application
Physical
Session
Présentation
Transport
Network
Data link
Device A
Message
Transport protocole: TCPUDP
1
2
3
4
5
6
7
Mostly used as framework for other network architectures. e.g TCP IP
Data linkData link Data link
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OSI versus TCP IP
o THE SEVEN OSI LAYERS
o OSI’s PROTOCOLS DATA TRANSMISSION
o TCP/IP MODEL
o TCP/IP NETWORKS SERVICES
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OSI’s PROTOCOLS DATA TRANSMISSION
Following a downstream flow (up to down):
Every layer receives data from the upper layer, adds its own controlinformations (overheads) before transmitting the new message to the bottom layer
E 2 E 3 E 4 M1 Q2 E 2 E 3 E 4 M2 Q2
E 3 E 4 M1 E 3 E 4 M2
E 4 M1E 4 M1
M
M
m
E 2 E 3 E 4 M1 Q2 E 2 E 3 E 4 M 2 Q 2
E 3 E 4 M1 E 3 E 4 M2
E 4 M2E 4 M2
M
M
m Layer 7 protocol
Layer 6 protocol
Layer 5 protocol
Layer 2 protocol
Layer 3 protocol
Layer 4 protocol
Layer Transmitted Received
7
6
5
4
3
1
interface 6/7
interface 5/6
interface 6/7
interface 5/6
Sender Receiver
2
DEVICES -
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OSI versus TCP/IP
ISO has started recommended OSI by end of 70’s
TCP IP was already adopted and in use
There are very few OSI-based systems running
Nearly all the networking softwares and protocols are built on
TCP IP model
OSI specifications are very complicated to implement as
compare to TCP IP.
OSI is a 7 layers model and TCP IP, 5.
OSI is has a better description of networks and its services.
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TCP/IP MODEL
Application
TCP
Application
UDP
IP
Hardware/Wired interfaces
OSI 5-7
OSI 4
OSI 3
OSI 1-2
Internet softwares are built on TCP/IP model
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TCP/IP NETWORKS SERVICES
The TCP/IP layers controls the network and achieve the following tasks:
• Data switching,• Packets routing• Flow control• Connexions,...
Two types of services are offered:
• Datagram or best effort.
• Virtual circuit or reliable delivery
A
BD
C
Datagram
A
BD
C
Virtual Circuit (V.C)
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WHAT ABOUT NETWORKS?
o INTERCONNECTED NETWORKS
o LOCAL NETWORKS STANDARDS
o IRQ (Interrupted Request) AND ERRORS PROCESSING
o SEQUENCE NUMBERS
o FLOW CONTROL MECHANISMS
o THE NETWORK LAYER
o SWITCHING TECHNIQUES
o ROUTING
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INTERCONNECTED NETWORKS
Modem101001 Modem
101001PSTN
MMMux
R
B
Satellite
Sub-network (e.g. X.25)
R
R
Components of a network•Repeater• Bridge• Router• Gateway• LAN• MAN• WAN
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The official standards for Local networks are IEEE 802 standards
• IEEE 802.3 CSMA\CD (Local Area Network e.g Ethernet)• IEEE 802.4 Token Bus• IEEE 802.5 Token Ring• IEEE 802.6 MAN (Metropolitan Area Network)• IEEE 802.11 WLAN (Wireless LAN)• IEEE 802.2 describes Datalink layer.
IEEE 802.2 Link Layer Control
IEE
E 8
02
.3
CS
MA
/CD
IEE
E 8
02
.4
To
ke
n B
us
IEE
E 8
02
.5
To
ke
n R
ing
IEE
E 8
02
.6
MA
N
MAC
LLC
PHYSICAL LAYER
LOCAL NETWORKS STANDARDS
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I(N)
Ack(N)
I(N+1)
Ack(N+1)
Timeout
I(N)
Timeout
Expiré
I(N)
Ack(N)
Erreur
Ack(N)
I(N)
Nack(N)
Timeout
I(N)Erreur
Ack(N)
I(N)
Timeout
Expiré
I(N)
Ack(N)
Erreur
Ack(N)
IRQ (Interrupted Request) AND ERRORS PROCESSING
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To avoid repeating message transmission:
A counter is used to make the difference between a Frame and the Frame that comes after:
I(0)
Timeout
Expiré
I(0)
Ack(N)
Erreur
Ack(0)
Livré
Ignoré
I(1)
Livré
SEQUENCE NUMBERS
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To control the flow, two techniques are used:
• Stop and Wait.
• Sliding window
• Credits technique:
FLOW CONTROL MECHANISMS
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Routing consists of conveying data through the network.
All the routing techniques a based on minimal-cost policies: Proportionnal to the network capacity
• Proportionnal to the traffic load of the line• In relation with capacity and load • Equal to the length and amount of paquets in the waiting queued on this node
Network
Data link
Physical
Network
Data link
Physical
Network
Data link
Physical
Network
Data link
Physical
THE NETWORK LAYER
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o When a message is transmitted between two nodes, it follows a dedicated path.o Sometimes, due to efficiency purposes, a message is cutted into small pieces o These techniques depend on switches problems.
Switching node
HôteSous-réseau
1
Node 1
SWITCHING TECHNIQUES
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Switching modes:
•circuits switching
•messages switching
•paquets switching
•cells switching
•Routing
SWITCHING TECHNIQUES (2)
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A B C D
E F G H
I J K L
A B C D E F G H I J K L
From J to:
0 12 25 40 14 23 18 17 21 9 24 29
20 31 19 8 30 19 6 0 14 7 22 9
21 28 36 24 22 40 31 19 22 10 0 9
A A I H I I H H I K K
8 20 28 20 17 30 18 12 10 0 6 15
From A
From H
From K
24 36 18 27 7 20 31 20 0 11 22 9
From I
Tables received by J from its neighbors New delay
Computed by J
Delay JA = 8
Delay JI = 10
Delay JH = 12
Delay JK = 6
J Table
If J need to compute its new path towards G,it obtains the best cost through H, that is a total amountOf 18 (JH = 12 et HG = 6).
Distributed routing techniques:RIP, OSPF,...
ROUTING
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New J table gives on the left the distance of the best route and on the rigth column, the next hope to take.
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TCP IP
o TCP/IP PROTOCOLS
o THE IP PROTOCOL
o IP ADRESSES
o THE TCP PROTOCOL
o THE UDP PROTCOL
o SERVICES DEDICATED PORTS
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Internet softwares are built on TCP/IP model :
FTP,TELNET, SMTP, HTTP
TCP UDP
IP
APPLICATIONS
802.2 LLC Slip, HDLC, PPP
Ethernet, Token Ring, ...
TRANSPORT
NETWORK
DATA LINK
PHYSICAL
TCP/IP PROTOCOLS
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Paquet identification
Version Header lenght Type of service Total IP paquet lenght
Flags Relative position
015 31
Lifetime counter Protocol Checksum
Source Adress
Destination Adress
Options Bourrage
Data
THE IP PROTOCOL
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8
0
0 24 32
Network AdressNetid
Host Adress Hostid
1 1
Class A
Class B
Class C
016
Network AdressNetid Host Adress
Hostid1 0
32
0
Network AdressNetid
Host Adress Hostid
0
32
IP ADRESSES
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A C K
0 15 31
Zone de conrôle d'erreur (Checksum)
Bourrage
Data
Source port Adress Destination port Adress
Sequence Number
Acknowledgement number
ReservedU R G
SYN
E ND
R S T
P S H
Options
Checksum field Emergency Area
Sliding windowHeader lenght
THE TCP PROTOCOL
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0 15 31
Data
Source port Adress Destination port Adress
Length Checksum
There is no delivery warranty: best effort
THE UDP PROTCOL
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Number Name Description5 RJE Remote Job Entry7 ECHO Echo11 USERS Active Users13 DAYTIME Daytime20 FTP-DATA File Transfert Data21 FTP-CONTROL File Transfert Control23 TELNET Telent25 SMTP Simple Mail42 TIME Time43 NAMESERV Host Name sever53 NICKNAME Who Is53 DOMAIN Domain Name Sever67 BOOTPS Bootstrap Server68 BOOTPC Bootstrap Client69 TFTP Trivial FTP79 FINGER Finger80 HTTP Web Server102 ISO-TSAP ISO transport103 X400 X400
Source and destination port adresses are the applications’access points,.
TCP identify an application with its dedicated port number
SERVICES DEDICATED PORTS
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