Network Review
Advanced Computer Networks
By: Mahdi Sadeghizadeh
Website: Sadeghizadeh.ir
1
Network Review

Computer network A collection of computing
devices that are connected in various ways in
order to communicate and share resources.
 Advantages of networks
•
•
•
•
•
Communications
Data & Resources sharing
Reliability
Cost reduction
Scalability .
Mahdi Sadeghizadeh
 Disadvantages of networks
•
•
•
•
Website: Sadeghizadeh.ir
Security Issues
Rapid spread of Viruses
Expensive Setup
Dependency on the Main File Server
Advanced Networks
2
Network Architectures

Client/Server Architecture

Peer-to-Peer Architecture
Mahdi Sadeghizadeh
Website: Sadeghizadeh.ir
Advanced Networks
3
Types of Servers







File Server
Internet Server
Email Server
DNS Server
RAS Server
Application Service Provider (ASP)
Storage Service Provider (SSP)
Mahdi Sadeghizadeh
Website: Sadeghizadeh.ir
Advanced Networks
4
Network Topologies

Various configurations, called topologies:
 Bus
topology
 Ring
 Star
topology
topology
 Mesh
 Tree
topology
topology
Mahdi Sadeghizadeh
Website: Sadeghizadeh.ir
Advanced Networks
5
Types of Networks
WAN
Personal Area Network
 Home Area Network
 Local Area Networks
 Campus Area Network
 Metropolitan Area Networks
 Wide Area Networks

Mahdi Sadeghizadeh
Website: Sadeghizadeh.ir
Advanced Networks
6
Comparison Of Networks
 An internet is a group of
networks linked together with
routers in a way that allows an
application program on any
station on any network in the
internet to be able to
communicate with an
application program on another
station on any other network.
Single Network
Routers
Packet
Single Network
Mahdi Sadeghizadeh
Website: Sadeghizadeh.ir
Route
Advanced Networks
7
Internet
Internet Usage
Traditional applications (1970 – 1990)
 E-mail
 News
 Remote login
 File transfer
Architecture
of
the Internet
Mahdi Sadeghizadeh
Website: Sadeghizadeh.ir
Advanced Networks
8
Network Equipments
Transmission Media
Network links

Guided ― wires, cables
 Twisted-Pair cables
 Coaxial
cables
 Fiber-optic cables

Unguided ― wireless transmission,
e.g. radio, microwave, infrared, sound, sonar
Mahdi Sadeghizadeh
Website: Sadeghizadeh.ir
Advanced Networks
11
Network Equipments
Network nodes








network interface controller (NICs)
(MOdulator-DEModulator)
are
used
to forwards
connect
network
nodes
via
A
Arepeater
bridge
is is
can
a network
an
connect
electronic
twodevice
different
for
controlling
that
types
receives
of
network
topologies.
afilters
network
security
and
router
an
internetworking
device
that
packets
repeater AModems
Afirewall
network
switch
is a device
device
that
forwards
and
OSIsignal,
layer
wire
not
designed
for
digital
network
traffic,
orhardware
for wireless.
A
network
interface
(NIC)
is computer
that
access
cleans
A
rules.
itoriginally
network
of
Firewalls
unnecessary
bridge
are
connects
noise,
typically
and
and
configured
regenerates
filters
traffic
toaddresses
it.reject
The
between
signal
access
two
isTo
between
networks
bycontroller
processing
the
routing
information
included
2 Or,
datagrams
between
ports
based
on
the
MAC
in
the
A
hub
is
a
multiport
repeater
that
retransmits
a
signal
do
this one
more
frequencies
areability
modulated
by
thethe
digital
signal
toan
hub
provides
aorsegments
computer
with
the
tooraccess
transmission
requests
retransmitted
network
from
unrecognized
at
a
higher
at
the
power
data
sources
link
level,
while
layer
to
allowing
(layer
the
other
2)
actions
of
side
the
OSI
of
from
in
the
packet
or
datagram
(Internet
protocol
information
from
packets.
A
switch
is distinct
from
a hubtoingive
thatthe
it only
forwards
on all
ports
produce
an
analog
signal
that can
be tailored
required
properties
media,
and
has
the
ability
to
process
low-level
network
recognized
obstruction,
model
to
ones.
form
so
that
a
single
the
signal
network.
can
cover
longer
distances
without
Network
layer
(layer
3)).
thetransmission.
frames to the
physical
involved
in the
communication
bridge
for
Modems
are ports
commonly
used for
telephone
lines, using a
information.
degradation.
ratherSubscriber
than all ports
Digital
Line connected.
technology. It can be thought of as a multiswitch
port bridge.
router
modem
firewall
Mahdi Sadeghizadeh
Website: Sadeghizadeh.ir
Advanced Networks
12
Multiplexing



In telecommunications and computer networks, multiplexing is a method by which
multiple analog message signals or digital data streams are combined into one signal over
a shared medium. The aim is to share an expensive resource.
The multiplexed signal is transmitted over a communication channel, which may be a
physical transmission medium. A reverse process, known as demultiplexing, can extract
the original channels on the receiver side.
Types of multiplexing







In wired communication, space-division
Space-division multiplexing (SDM)
Frequency-division multiplexing (FDM) multiplexing simply implies different
wires for different channels.
wavelength-division multiplexing (WDMpoint-to-point
)
In wireless communication, space-division
Time-division multiplexing (TDM)
Polarization-division multiplexing (PDM)multiplexing is achieved by multiple
antenna elements forming a phased array
Orbital angular momentum multiplexing
antenna.
Code-division multiplexing (CDM)
Mahdi Sadeghizadeh
Website: Sadeghizadeh.ir
Advanced Networks
13
Switching Decision

In large networks there might be multiple paths linking sender and
receiver. Information may be switched as it travels through various
communication channels. There are four typical switching techniques
available for digital traffic:
 Circuit Switching
 Packet
Switching
 Message
 Cell
Circuit switching is a methodology of implementing a
Packet
switching
is a digital
telecommunications
network
in whichnetworking
two network nodes
communications
method
that
groups
all through
establish a dedicated communications channel (circuit)
the
network before
may communicate.
Thetype,
circuit
transmitted
datathe– nodes
regardless
of content,
guarantees the full bandwidth of the channel and remains
or structure – into suitably sized blocks, called
connected for the duration of the communication session.
packets.
Switching
Switching
Mahdi Sadeghizadeh
Website: Sadeghizadeh.ir
Advanced Networks
14
Communications protocols

A communications protocol is a set of rules for exchanging
information over network links.
 Ethernet
 Internet
Protocol Suite
 SONET/SDH
 Asynchronous
Mahdi Sadeghizadeh
Transfer Mode
Website: Sadeghizadeh.ir
Advanced Networks
15
Network Software

Layer Programming:



The OSI Reference Model
The TCP/IP Reference Model
Communications protocols: A communications protocol is
a set of rules for exchanging information over network links.

Layer services: Connection-Oriented & Connectionless services.
Mahdi Sadeghizadeh
Website: Sadeghizadeh.ir
Advanced Networks
16
Protocol Hierarchies

Layers, protocols, and interfaces
Mahdi Sadeghizadeh
Website: Sadeghizadeh.ir
Example
Advanced Networks
17
Protocol Hierarchies
 Example information flow supporting virtual communication in layer 5
Mahdi Sadeghizadeh
Website: Sadeghizadeh.ir
Advanced Networks
18
Reference Models


The OSI Reference Model
The TCP/IP Reference Model
Mahdi Sadeghizadeh
Website: Sadeghizadeh.ir
Advanced Networks
19
OSI Reference Model

Network
layer

Physical
layer
layer
Data
Link
layer
 Transport
Application
layer
Presentation
Session
layer

The
a virtual
of
the
end-to-end
physical
layer
connection
islayer
tofor
govern
so
that
the
data
main
Functions
of
the
network
include:

Faraming:
Converts
from
upper
layers

The
application
layer
isisdata
the
OSI
layer
closest
to
the

The
presentation
layer
responsible
the
delivery
Provides
Thepurpose
session
layer
controls
the
dialogues
(connections)
transferred
transmission
between
of
bits
two
one
hosts
at aframes
time
will
over
arrive
aconnectivity
wire,
without
radio,
errors
end
user,
which
means
both
the
application
and
of
information
to OSI
the
application
into
logical
packages
or
or
 formatting
Routing
and
addressing:
Provides
between
computers.
It establishes,
manages
and
and
or
other
inand
the
connection
correct
order.
between
alayer
station
and
a software
switch,
layer
and
the
interact
directly
the
layer
for
further
processing
or
display.
Services:
path
selection
between
twowith
systems
terminates
theuser
connections
between
the
local
and
Encapsulation
of
network
data
packets
between
pairs
of switches,
orconvenient
between
aservices:
switch
application.
 The
layer
provides
remote
application.
transport
Data
conversion:
Translates
data from
the and
Congestion
Control
into
frames
aApplication-layer
router.

functions
include
: to
Application
layer
into
antypically
intermediary
format
 connection-oriented
data
stream
support,

Allows
two
applications
on
different
computers
Solve
the
problem
of
Heterogeneous
Networks
 Converts
logical
frames
into
raw
bits
that
are
 Defines
mechanical,
functional,
procedural
and
establish
dialog
control
Reliability:
identifying
communication
partners
Encryption,
Decryption
and
compresses
data

the problem
of Packet Loss
transmitted
bysolve
the
Physical
layer
 electrical
Protocols:
aspects
of networking
 Regulates
which
side
transmits
 Character
determining
resource
availability
code
translation

control
 flow
IPv4/IPv6,
Internet
Protocol

Error
detection
and
correction:
The data
 Includes connectors, circuits, voltage levels
and link

Determines
the
time
and
length
of
the
transmission
Multiplexing:
synchronizing
communication
 Protocols:

Ports
can
provide
multiple
ICMP,
Internet
Control
Message
Protocol
layer
provides
a reliable
link
between
two
grounding
endpoints
on
a
single
node.
Apple
Filing
(AFP)

Protocols:
 directly
It
for: Protocol
provides
IGMP,
Internet
Group
Management
Protocol
connected
nodes,
by detecting
and

Architecture
 Protocols:

Remote
loginComputing
category:
Telnet,

IPsec,
Internet
Protocol
Security
 Independent
Authentication
and
Authorization
possibly
correcting
errors
that SSH
may(ICA)
occur in the
Voltage
levels
 TCP,
Transmission
Control
Protocol

NBF,
NetBIOS
Frames protocol

Lightweight
Presentation
Protocol
(LPP)
 IPX,
transfer
category:
FTP,
TFTP

Internetwork
Packet
Exchange
 File
full-duplex,
half-duplex,
or
simplex
operation
physical
layer.
To represent 1s and
0s
 UDP, User Datagram Protocol
 RDP,
Reliable Datagram Protocol

Data
Representation
(NDR)
 Network
Electronic
mail
category: Protocol
SMTP,
IMAP,
POP

RIP,
Routing
Information

Session
restoration
(checkpointing
and
recovery)
 SPX, Sequenced
Packet
Exchange
 Flow
control:
Solve
the problem
of mismatch
ATP,
AppleTalk
Transaction
Protocol

(a services
remote
terminal
access
 Telnet
Support
category:
DNS,protocol)
RARP, …

DDP,
Datagram
Delivery
Protocol
 receiver
SST,
Stream
Transport
 between
FCP,
Fiber Channel
Protocol
 Adjournment,
termination
andStructured
restart
procedures
transmitter
and
speed.

Data
Representation
(XDR),
 eXternal
Web:the
HTTP,
…

ARP,
Address
Resolution
Protocol
……
Connectors
…
Mahdi Sadeghizadeh
Website: Sadeghizadeh.ir
Transmission Media
Advanced Networks
20
OSI Reference Model
Mahdi Sadeghizadeh
Website: Sadeghizadeh.ir
Advanced Networks
21
Comparing OSI and TCP/IP Models





There is exact separation between Services, interfaces and protocols
concepts in OSI model.
The OSI Reference Model is based on OOP.
OSI designers had not enough designing experience.
TCP/IP is a practical standard.
There is not enough security in TCP/IP
Mahdi Sadeghizadeh
Website: Sadeghizadeh.ir
Advanced Networks
22
Thank You
23