INE4481 DISTRIBUTED DATABASES & CLIENT-SERVER ARCHITECTURES

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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

A.Obaid-Wilfried Probst – Rufin Soh INE4481 DISTRIBUTED DATABASES & CLIENT-SERVER ARCHITECTURES

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

3

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.


5

Networks (1970 - 1980)

Token Ring

Ethernet


6

Inter-networks (1980 - 1990)

Token Ring

Ethernet

FDDI

Serial WAN Connexion


7

Internet: Network of networks

ATMSwitcher

Router


8

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


9

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


10

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 -


12

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.


13

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)


15

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


17

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


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


28

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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