Chapter 2 - OoCities

warmersafternoonNetworking and Communications

Oct 23, 2013 (3 years and 8 months ago)

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1


Chapter 2.

Networks and
and
communication
protocols



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2


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

DAT䄠
T剁RSMISSION

o
T䍐LIP MO䑅L

o
T䍐LIP NETWO剋S⁓ER噉䍅S

A.Obaid
-
Wilfried Probst


Rufin Soh


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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

3


NETWORKS
HISTORY

o
The steps towards Internet :

o
Centralized Processing (1960
-

1970)

o
Networks (1970
-

1980)

o
Inter
-
networks (1980
-

1990)

o
Internet: Network of networks

A.Obaid
-
Wilfried Probst


Rufin Soh


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4

Centralized Processing (1960
-

1970)

Mainframe

Host A

Mini
-
computer

Host B

terminal

Remote terminal

R.V.A.

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5

Networks (1970
-

1980)

Token

Ring

Ethernet

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6

Inter
-
networks (1980
-

1990)

Token

Ring

Ethernet

FDDI

Serial WAN

Connexion

A.Obaid
-
Wilfried Probst


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7

Internet: Network of networks

ATM

Switcher

Router

A.Obaid
-
Wilfried Probst


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8

RECALLS

ON

NETWORK SYSTEMS


The reference model for open systems interconnection is OSI.

o
Used to structured communication software components.

o
Created by the International Standard Organisation ISO.

o
Intended to enable interoperablity between protocols

and between networks applications.


OSI model:

Machine

A

Machine

B

Layer

N+1

layer

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 link

Data link

Data link

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OSI versus TCP IP

o
THE SEVEN OSI LAYERS

o
OSI’s PROTOCOLS

DA呁 呒A乓N䥓卉低

o
呃倯䥐PM佄䕌

o
呃倯䥐P久呗NR䭓K卅Ss䥃䕓

11


OSI’s

PROTOCOLS


DATA TRANSMISSION


Following a downstream flow (up to down):


Every layer receives data from the upper layer, adds its own control

informations (overheads) before transmitting the new message to the

bottom layer

E

2

E

3

E

4

M

1

Q

2

E

2

E

3

E

4

M

2

Q

2

E

3

E

4

M

1

E

3

E

4

M

2

E

4

M

1

E

4

M

1

M

M

m

E

2

E

3

E

4

M

1

Q

2

E

2

E

3

E

4

M

2

Q

2

E

3

E

4

M

1

E

3

E

4

M

2

E

4

M

2

E

4

M

2

M

M

m


Layer

7

p
rotocol


Layer

6 p
rotocol


Layer

5 p
rotocol


Layer

2 p
rotocol


Layer

3 p
rotocol


Layer

4 p
rotocol

Layer

Transmi
tted

R
eceived

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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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.

A.Obaid
-
Wilfried Probst


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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

A.Obaid
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Wilfried Probst


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14


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

B

D

C

Datagram

A

B

D

C

Virtual Circuit (V.C)

A.Obaid
-
Wilfried Probst


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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

16

INTERCONNECTED NETWORKS

Modem

101001

Modem

101001

PSTN

M

M

Mux

R

B

Satellite

Sub
-
network

(e.g. X.25)

R

R

Components of a network


Repeater



Bridge



Router



Gateway



LAN



MAN



WAN

A.Obaid
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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

IEEE 802.3

CSMA/CD

IEEE 802.4

Token Bus

IEEE 802.6

MAN

MAC

LLC

PHYSICAL LAYER

LOCAL NETWORKS STANDARDS


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Timeout

Timeout

Expiré

Erreur

Timeout

Erreur

Timeout

Expiré

Erreur

IRQ (Interrupted Request) AND ERRORS
PROCESSING


A.Obaid
-
Wilfried Probst


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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:







Timeout

Expiré

Erreur

Livré

Ignoré

Livré

SEQUENCE NUMBERS


A.Obaid
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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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21

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




THE NETWORK LAYER


A.Obaid
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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

Hôte

Sous
-
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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If J need to compute its new path towards G,

it obtains the best cost through H, that is a total amount

Of 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.

25

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

26

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

A.Obaid
-
Wilfried Probst


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Paquet identification

Version

Header lenght

Type of service

Total IP paquet lenght

Flags

Relative position

0

15

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 Adress

Netid

Host Adress

Hostid

1

1

Class A

Class B

Class C

0

16

Network Adress

Netid

Host Adress

Hostid

1

0

32

0

Network
Adress

Netid

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

Reserved

U

R

G

S

Y

N

E

N

D

R

S

T

P

S

H

Options

Checksum field

Emergency Area

Sliding window

Header

lenght

THE TCP PROTOCOL


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30

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

Description

5

RJE

Remote Job Entry

7

ECHO

Echo

11

USERS

Active Users

13

DAYTIME

Daytime

20

FTP
-
DATA

File Transfert Data

21

FTP
-
CONTROL

File Transfert Control

23

TELNET

Telent

25

SMTP

Simple Mail

42

TIME

Time

43

NAMESERV

Host Name sever

53

NICKNAME

Who Is

53

DOMAIN

Domain Name Sever

67

BOOTPS

Bootstrap Server

68

BOOTPC

Bootstrap Client

69

TFTP

Trivial FTP

79

FINGER

Finger

80

HTTP

Web Server

102

ISO
-
TSAP

ISO transport

103

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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