Download Communication & Newtorking in Information Technology

Communication &
Networking:
An Overview
Debashis Saha
MIS Group, IIM Calcutta
E-mail: [email protected]
Network Management
OVERVIEW
@Debashis Saha, IIM Calcutta
May 25, 2017
Organization
• Communication Systems
• Networking Fundamentals
• The INTERNET
• Network Security
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
Simple Communication Model
Source
Destination
Transmission
media
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
Example
client program
server
communications
channel
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
Communication System
Noise
Carrier
Source
Modulator
Demodulator
Sink
Transmission
media
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
Data Communication Model
DTE
Computer
Network Management
DCE
Modem
OVERVIEW
DCE
Modem
DTE
Computer
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@Debashis Saha, IIM Calcutta
May 25, 2017
Modes of Communication
Simplex
communications
Half-duplex (HDX)
or
communications
Full-duplex (FDX)
communications
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
Communication Ports
9-pin D-type
9-pin or 25-pin D-type
male connector (COM1:)
male connector (COM2:)
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
Transmission Media
• Wired
– Twisted pair, Coaxial cable, FO
• Wireless
– Short range
• Infrared
– Long Range
• Microwave
• Satellite
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
Transmission Media
Inner
conductor
Metal sheath
Insulating outer conductor
Coaxial
cable
Fibre
optic
cable
Inner cladding
Inner fibre (glass)
(glass)
Outer cladding
(PVC)
Twisted-pair
cable
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
Telephone Network
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
Cable TV Network
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
Multiplexing
• Time-Division Multiplexing (TDM)
• Frequency-Division Multiplexing (FDM)
• Statistical Time-Division Multiplexing (STDM)
L1
R1
L2
R2
L3
Network Management
Switch 1
Switch 2
OVERVIEW
R3
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@Debashis Saha, IIM Calcutta
May 25, 2017
Networks
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
Categories
• Communication Networks
– PSTN
• Computer Networks
– INTERNET
• Integrated Networks
– Computer & Communication Networks
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
Building Blocks
• Nodes: PC, special-purpose hardware…
– hosts
– switches
• Links: coax cable, optical fiber…
– point-to-point
– multiple access
Network Management
OVERVIEW
…
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@Debashis Saha, IIM Calcutta
May 25, 2017
Switched Networks
• A network can be defined recursively as...
– two or more nodes
connected by a
link, or
Network Management
OVERVIEW
– two or more networks
connected by two or
more nodes
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@Debashis Saha, IIM Calcutta
May 25, 2017
Switching Strategies
• Circuit switching: carry bit streams
– original telephone network
• Packet switching: store-and-forward messages
– Internet
• See the schematic diagram next
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
Ckt Vs. Pkt Switching
Circuitswitching
PSE
fixed route
Packetswitching
possible routes
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
Addressing and Routing
• Address: byte-string that identifies a node
– usually unique
• Routing: process of forwarding messages to the
destination node based on its address
• Types of addresses
– unicast: node-specific
– broadcast: all nodes on the network
– multicast: some subset of nodes on the
network
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
What Goes Wrong in the
Network?
• Bit-level errors (electrical interference)
• Packet-level errors (congestion)
• Link and node failures
• Messages are delayed
• Messages are deliver out-of-order
• Third parties eavesdrop
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
Layering
• Use abstractions to hide complexity
• Abstraction naturally lead to layering
• Alternative abstractions at each layer
Application programs
Request/reply Message stream
channel
channel
Host-to-host connectivity
Hardware
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
Protocols
• Building blocks of a network architecture
• Each protocol object has two different interfaces
– service interface: operations on this
protocol
– peer-to-peer interface: messages
exchanged with peer
• Term “protocol” is overloaded
– specification of peer-to-peer interface
– module that implements this interface
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
Interfaces
Host 1
High-level
object
Protocol
Network Management
Host 2
Service
interface
Peer-to-peer
interface
OVERVIEW
High-level
object
Protocol
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@Debashis Saha, IIM Calcutta
May 25, 2017
ISO-OSI 7 Layer Ref. Model
DATA
DATA
Virtual Data Flow
DATA
Application
A
DATA
Presentation
P
A
DATA
Session
S
P
A
DATA
Transport
T
S
P
A
DATA
Network
N T
S
P
A
DATA
Data Link
N T
S
P
A
DATA
Application
Presentation
Session
Transport
Network
Data Link
Physical
D
D
Physical
Actual Data Flow
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
Data Flow in Layered Model
DATA
DATA
Virtual Data Flow
Application
Application
Presentation
Presentation
Session
Session
Transport
Transport
Network
Network
Data Link
Data Link
Physical
Physical
User application. process
and management functions
Data interpretation, format
and control transformation
Administration and control
of session between two nodes
Network transparent data transfer
and transmission control
Routing, switching and flow
control over a network
Maintain and release data:
link, error and flow control
Electrical and mechanical
characteristics
Actual Data Flow
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
Logical View of Layers
NETWORK A
NETWORK B
Session
Data Link
Transport
N6
N1
N5
N4
N2
N7
N8
N3
Network
Physical
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
Types of Networks
• LAN
– Local area
• MAN
– Metropolitan area
• WAN
– Wide area
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
Ring, Star & Bus LAN
Ring network
Star network
central
server
Bus network
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
IEEE LAN Standards
LLC
MAC
LLC
LAN
MAC
Physical
Physical
Logical link control (LLC)
IEEE 802.2
Data link
Physical
OSI model
Network Management
Media access
control (MAC)
IEEE 802.5
Token ring
OVERVIEW
Media access
control (MAC)
IEEE 802.3
CSMA/CD
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@Debashis Saha, IIM Calcutta
May 25, 2017
Campus Wide LAN
MECH_1
INSTR_1
Fan-out
box
Fan-out
box
Ethernet backbone
Fan-out
box
Fan-out
box
PRODUCTION_1
Fan-out
box
ADMIN_1
Fan-out
box
PRODUCTION_2
Network Management
ELECT_1
Fan-out
box
ADMIN_2
OVERVIEW
ELECT_1 can act
as a stand-alone
network if required
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@Debashis Saha, IIM Calcutta
May 25, 2017
Internetworking
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
Definition
• An internetwork is an interconnected collection
of independent networks
– Each independent network is often
referred to as an autonomous system
(AS)
• Internetwork is the generic name to any kind of
network interconnection
• The INTERNET is a special internetwork that
uses TCP/IP protocol stack
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
Difference with network?
• A network is a collection of interconnected computers
• An internetwork is a collection of interconnected
networks (or AS’s)
Network 1 (Ethernet)
H7
H2
H1
R3
H8
H3
Network 4
(point-to-point)
Network 2 (Ethernet)
R1
R2
H4
Network 3 (FDDI)
H5
Network Management
OVERVIEW
H6
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@Debashis Saha, IIM Calcutta
May 25, 2017
Various Internetworking Cases
• LAN-LAN
– EE LAN to CSE LAN in a campus network
• LAN-WAN
– office LAN to the INTERNET
• WAN-WAN
– ERNET to VSNL-net
• LAN-WAN-LAN
– two offices connected via the INTERNET
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
Practical Internetworking Scenario
• LAN for small domains of computers
• LAN-LAN interconnection for a campus
• LAN-WAN interconnection for INTERNET
connectivity
• LAN-WAN-LAN interconnection for connectivity
between distant computers
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
A common Example
(LAN-LAN, LAN-WAN, LAN-WAN-LAN)
LAN B
LAN A
Gateway
Bridge
or modem
LAN C
Local network
backbone
Wide area
network
LAN D
connection
Wide area
network
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
Internetworking Devices
•
•
•
•
Repeater (layer 1)
bit-level
Bridge
(layer 2)
frame-level
Router
(layer 3)
packet-level
Gateway
(layer 4-7)
message-level
– Transport layer gateway
level
– Application layer gateway
level
Network Management
OVERVIEW
TPDU-
APDU-
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@Debashis Saha, IIM Calcutta
May 25, 2017
The INTERNET
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
Early History
• 1969, Dec – ARPANET went on air:: US DoD
• 1974 – TCP/IP discovered :: Cerf & Kahn
• 1983, Jan 01 – TCP/IP became the official
protocol
• MILNET is isolated from ARPANET
• 1990 – the Internet takes over, ARPANET dies
• NSFNET is merged with ARPANET
• 1992 – the Internet Society was set up
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
The Internet Structure- Recent
Past
NSFNET backbone
Stanford
ISU
BARRNET
MidNet
regional
regional
Westnet
regional
Berkeley
PARC
UNM
NCAR
UNL
KU
UA
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
The Internet Structure- Today
Large corporation
“Consumer
” ISP
Peering
point
Backbone service provider
Peering
point
“ Consumer
” ISP
Large corporation
“Consumer
”ISP
Small
corporation
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
Traditional use of the Internet
• E-mail (SMTP)
– Pine, outlook express, hotmail, yahoo, etc
• News (NNTP)
– Usenet
• Remote login (Telnet)
– Rlogin
• File transfer (FTP)
– CuteFTP, download
• Browsing (HTTP)
– WWW, Explorer, Netscape
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
How to be on the Internet?
• A machine is capable to be on the Internet, if it
has
–
–
–
–
An IP address
TCP/IP support
Ability to send IP packets
Physical connectivity
• Today TCP/IP is built into most OS’s
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
Connecting from Home
•
•
•
•
•
•
•
Windows/Linux has TCP/IP inbuilt
Configure TCP/IP for your ISP & modem
Configure dial-up connection
Connect modem to your PC (connectivity)
Dial ISP’s # using PPP
Login and get temporary IP
Start browser or e-mail client
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
Connecting to ISP via Modem
Modem
Modem
33.6 Kbps
Modem
Public switched
telecommunication
network
Modem
Modem
56 Kbps
ISP Server
Modem
stack
Network Management
OVERVIEW
INTERNET
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@Debashis Saha, IIM Calcutta
May 25, 2017
TCP/IP Stack
• Unlike OSI, it is a 5 layer architecture
– Session & presentation layers are
merged into application layer
• Lower 2 layers are not specified
– Any LAN can fit into IP
– This is a prime reason for its popularity
• Has its origin in UNIX OS
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
TCP/IP Architecture
Application
FTP/TELNET
Application
TCP
TCP
IP
IP
Network
controller
software
Network
controller
software
Computer on
network A
Network Management
Physical medium
OVERVIEW
Computer on
network B
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@Debashis Saha, IIM Calcutta
May 25, 2017
Internet Routing
• Overview
– Forwarding vs. routing
• 2-level routing
– IGP and EGP
• Distance vector
• Link state
• Route calculation
– Dijkstra’s algorithm
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
INTERNET PROTOCOL
(IP)
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
Versions
• Two versions are there:
– Version 4 (IPv4)
• 32 bit address
– Version 6 (IPv6)
• 128 bit address
• Mobility support
– Mobile IP
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
Global IP Addresses
• Properties
– globally unique
– hierarchical: network + host
– 32/128 bit
• Dotted Decimal Notation
– 10.3.2.4
– 128.96.33.81
– 192.12.69.77
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
Subnetting
• Add another level to address/routing hierarchy: subnet
• Subnet masks define variable partition of host part
• Subnets visible only within site
Network number
Host number
Class B address
111111111111111111111111
00000000
Subnet mask (255.255.255.0)
Network number
Subnet ID
Host ID
Subnetted address
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
How are subnet masks
specified?
16 bits
8 bits
8 bits
Network ID = 128.138
Subnetid
Hostid
11111111 11111111
11111111
16 bits
00000000 255.255.255.0
10 bits
6 bits
Network ID = 128.138
Subnetid (241)
Hostid (78)
11111111 11111111
11111111 11
000000
Network Management
OVERVIEW
255.255.255.192
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@Debashis Saha, IIM Calcutta
May 25, 2017
IPv6
• Though CIDR has given IPv4 some breathing
space, its days are numbered.
• In 1990, IETF started work on a new version of
IP which will never run out of addresses
• In 19993, it is decided as IPv6
– Since IPv5 was already in use for an
experimental real-time streaming
protocol
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
INTERNET Domain Names
edu
gov
com
intel
sony
mil
usa
eece.napier.ac.uk
www.eece.napier.ac.uk
OVERVIEW
fr
ac
nec
ed
Network Management
uk
bath
napier
eece
cs
man
mmse
www
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@Debashis Saha, IIM Calcutta
May 25, 2017
Examples
• Hosts
iimcal.ac.in [domain name] 
203.197.69.17 [IP address] -->
80:23:A8:33:5B:9F [ethernet MAC
address]
• Files
/usr/llp/tmp/foo
(server, fileid)
• Users
Debashis Saha
Network Management
[email protected]
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
Network Security
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
Common Security Risks
Hacker
To test out someone's security system; steal
data
Businessman To discover a competitor's marketing
strategy
Accountant To embezzle money from a company
Stockbroker To deny a promise made via e-mail
Con man
To steal credit card numbers for sale
Student
To have fun snooping on peoples' e-mail
Terrorist
To destroy data (say by virus attack)
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
Security Measures
• Physical Layer:
covert channel,
spread-spectrum
• Data Link Layer: link encryption
• Network Layer: packet-filter
• Application Layer:firewall,
cryptography
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
Secret Key System
DES Key
DES Key
Alice
Network Management
Bob
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
SSL
• It is stream-based consisting of three phases
• In initial handshake phase, secure
communications are established
• In intermediate data transfer phase,
application-to-application dialog (with data
encryption) occurs
• In closing handshake phase, connection is
terminated
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
Looking Forward
Network Management
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
The Power of “O”
High data rate
~ Tbps
High reliability of
fibre ~ 30 years
YOUR
BUSINESS
Un-repeatered
over longer
distances
Network Management
Low error rate
< 10^(-6)
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
The Power of “M”
Consumer
oriented
Handy devices
YOUR
BUSINESS
Anywhere,
anytime
Network Management
Freedom for
movement
OVERVIEW
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@Debashis Saha, IIM Calcutta
May 25, 2017
Future = Optical + Mobile
• Wireless mobile communication has already
attracted global attraction
• DWDM optical technology is maturing at a
very high speed
• Future global trends showWide-spread adoption of wireless mobile
access to optical backbones
Network Management
OVERVIEW
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