network management overview communication
TRANSCRIPT
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Network Management OVERVIEW
Communication & Networking:
An Overview
Debashis SahaMIS Group, IIM Calcutta
E-mail: [email protected]
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April 11, 2023@Debashis Saha, IIM Calcutta
2Network Management OVERVIEW
Organization
•Communication Systems•Networking Fundamentals
•The INTERNET•Network Security
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April 11, 2023@Debashis Saha, IIM Calcutta
3Network Management OVERVIEW
Simple Communication Model
Source Destination
Transmission
media
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April 11, 2023@Debashis Saha, IIM Calcutta
4Network Management OVERVIEW
Example
client program server
communicationschannel
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April 11, 2023@Debashis Saha, IIM Calcutta
5Network Management OVERVIEW
Communication System
Source Modulator Demodulator Sink
Carrier
Noise
Transmissionmedia
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April 11, 2023@Debashis Saha, IIM Calcutta
6Network Management OVERVIEW
Data Communication Model
Modem
DCE
Modem
DCE
Computer
DTE
Computer
DTE
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April 11, 2023@Debashis Saha, IIM Calcutta
7Network Management OVERVIEW
Modes of Communication
Simplex
communications
Half-duplex (HDX)
communications
Full-duplex (FDX)
communications
or
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8Network Management OVERVIEW
Communication Ports
9-pin D-type
male connector (COM1:)
9-pin or 25-pin D-type
male connector (COM2:)
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9Network Management OVERVIEW
Transmission Media
• Wired– Twisted pair, Coaxial cable, FO
• Wireless– Short range
• Infrared
– Long Range• Microwave
• Satellite
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10Network Management OVERVIEW
Transmission MediaMetal sheath Inner
conductor
Insulating outer conductor
Coaxialcable
Twisted-paircable
Inner cladding(glass)Inner fibre
(glass)
Outer cladding(PVC)
Fibre opticcable
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April 11, 2023@Debashis Saha, IIM Calcutta
11Network Management OVERVIEW
Telephone Network
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12Network Management OVERVIEW
Cable TV Network
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13Network Management OVERVIEW
Multiplexing
• Time-Division Multiplexing (TDM)• Frequency-Division Multiplexing (FDM)• Statistical Time-Division Multiplexing (STDM)
L1
L2
L3
R1
R2
R3Switch 1 Switch 2
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14Network Management OVERVIEW
Networks
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15Network Management OVERVIEW
Categories
• Communication Networks– PSTN
• Computer Networks– INTERNET
• Integrated Networks– Computer & Communication
Networks
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16Network Management OVERVIEW
Building Blocks
• Nodes: PC, special-purpose hardware…– hosts– switches
• Links: coax cable, optical fiber…– point-to-point
– multiple access …
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17Network Management OVERVIEW
Switched Networks
– two or more nodes connected by a link, or
– two or more networks connected by two or more nodes
• A network can be defined recursively as...
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18Network Management OVERVIEW
Switching Strategies
• Circuit switching: carry bit streams– original telephone network
• Packet switching: store-and-forward messages– Internet
• See the schematic diagram next
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19Network Management OVERVIEW
Ckt Vs. Pkt Switching
Circuit-switching
Packet-switching
possible routes
fixed routePSE
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20Network Management OVERVIEW
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
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21Network Management OVERVIEW
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
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22Network Management OVERVIEW
Layering• Use abstractions to hide complexity• Abstraction naturally lead to layering• Alternative abstractions at each layer
Request/replychannel
Message streamchannel
Application programs
Hardware
Host-to-host connectivity
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April 11, 2023@Debashis Saha, IIM Calcutta
23Network Management OVERVIEW
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
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24Network Management OVERVIEW
Host 1
Protocol
Host 2
Protocol
High-levelobject
High-levelobject
Serviceinterface
Peer-to-peerinterface
Interfaces
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25Network Management OVERVIEW
ISO-OSI 7 Layer Ref. Model
Application
Session
Transport
Network
Data Link
Physical
Presentation
Application
Session
Transport
Network
Data Link
Physical
Presentation
DATA
DATA
DATA
DATA
DATA
DATA
A
A
A
A
A
P
P
P
P
S
S
S
T
TN
DATAAPSTND D
DATA DATA
Actual Data Flow
Virtual Data Flow
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26Network Management OVERVIEW
Data Flow in Layered Model
DATA DATA
Actual Data Flow
Virtual Data FlowUser application. processand management functionsData interpretation, formatand control transformation
Administration and controlof session between two nodes
Network transparent data transferand transmission controlRouting, switching and flowcontrol over a network
Maintain and release data:link, error and flow control
Electrical and mechanicalcharacteristics
Application
Session
Transport
Network
Data Link
Physical
Presentation
Application
Session
Transport
Network
Data Link
Physical
Presentation
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27Network Management OVERVIEW
Logical View of Layers
N1
N7
Session
Transport
Network
Physical
Data Link
N2
N3
N4
N6
N8
N5
NETWORK A NETWORK B
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28Network Management OVERVIEW
Types of Networks
• LAN– Local area
• MAN– Metropolitan area
• WAN– Wide area
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29Network Management OVERVIEW
Ring, Star & Bus LAN
Ring network
Bus network
Star network
centralserver
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30Network Management OVERVIEW
IEEE LAN Standards
Physical
MAC
LLC
Physical
MAC
LLC
LAN
Physical
Data link
Logical link control (LLC) IEEE 802.2
Media accesscontrol (MAC)IEEE 802.5 IEEE 802.3
Token ring CSMA/CDOSI model
Media accesscontrol (MAC)
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31Network Management OVERVIEW
Campus Wide LAN
PRODUCTION_1
PRODUCTION_2
ADMIN_1
ADMIN_2
ELECT_1
INSTR_1MECH_1
Ethernet backbone
ELECT_1 can actas a stand-alonenetwork if required
Fan-outbox
Fan-outbox
Fan-outbox
Fan-outbox
Fan-outbox
Fan-outbox
Fan-outbox
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32Network Management OVERVIEW
Internetworking
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33Network Management OVERVIEW
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
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34Network Management OVERVIEW
Difference with network?
• A network is a collection of interconnected computers• An internetwork is a collection of interconnected
networks (or AS’s)
R2
R1
H4
H5
H3H2H1
Network 2 (Ethernet)
Network 1 (Ethernet)
H6
Network 3 (FDDI)
Network 4(point-to-point)
H7 R3 H8
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35Network Management OVERVIEW
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
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36Network Management OVERVIEW
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
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37Network Management OVERVIEW
A common Example(LAN-LAN, LAN-WAN, LAN-WAN-LAN)
LAN A
LAN C
LAN D
Wide area
network
connection
Local network
backbone
Wide areanetwork
Gateway
or modem
LAN B
Bridge
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38Network Management OVERVIEW
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 TPDU-level
– Application layer gateway APDU-level
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39Network Management OVERVIEW
The INTERNET
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40Network Management OVERVIEW
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
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41Network Management OVERVIEW
The Internet Structure- Recent Past
NSFNET backboneStanford
BARRNET
regional
Berkeley
PARC
NCAR
UA
UNM
Westnet
regional
UNL KU
ISU
MidNet
regional…
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42Network Management OVERVIEW
The Internet Structure- Today
Backbone service provider
Peering
pointPeering
point
Large corporation
Large corporation
Small
corporation
“Consumer ” ISP
“Consumer ” ISP
“ Consumer ” ISP
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43Network Management OVERVIEW
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
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44Network Management OVERVIEW
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
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45Network Management OVERVIEW
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
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46Network Management OVERVIEW
Connecting to ISP via Modem
Modem
Modem
Modemstack
Modem
Modem33.6 Kbps
Modem56 Kbps
Public switchedtelecommunicationnetwork
ISP Server
INTERNET
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47Network Management OVERVIEW
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
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48Network Management OVERVIEW
TCP/IP Architecture
Computer onnetwork A Physical medium
FTP/TELNETApplication
TCP
IP
Application
TCP
IP
Networkcontrollersoftware
Networkcontrollersoftware
Computer onnetwork B
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49Network Management OVERVIEW
Internet Routing
• Overview– Forwarding vs. routing
• 2-level routing– IGP and EGP
• Distance vector• Link state• Route calculation
– Dijkstra’s algorithm
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50Network Management OVERVIEW
INTERNET PROTOCOL(IP)
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51Network Management OVERVIEW
Versions
• Two versions are there:– Version 4 (IPv4)
• 32 bit address
– Version 6 (IPv6)• 128 bit address
• Mobility support– Mobile IP
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52Network Management OVERVIEW
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
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53Network Management OVERVIEW
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
Subnet mask (255.255.255.0)
Subnetted address
111111111111111111111111 00000000
Network number Host IDSubnet ID
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54Network Management OVERVIEW
How are subnet masks specified?
Subnetid HostidNetwork ID = 128.138
16 bits 8 bits 8 bits
Subnetid (241) Hostid (78)Network ID = 128.138
16 bits 10 bits 6 bits
11111111 11111111 11111111 00000000 255.255.255.0
11111111 11111111 11111111 11 000000 255.255.255.192
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55Network Management OVERVIEW
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
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56Network Management OVERVIEW
INTERNET Domain Names
edu gov com mil usa uk fr
ac
ed bath napier man
eece cs mmseeece.napier.ac.uk
intel sony nec
wwwwww.eece.napier.ac.uk
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57Network Management OVERVIEW
Examples
• Hostsiimcal.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 [email protected]
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58Network Management OVERVIEW
Network Security
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April 11, 2023@Debashis Saha, IIM Calcutta
59Network Management OVERVIEW
Common Security RisksHacker To test out someone's security system; steal
dataBusinessman To discover a competitor's marketing
strategyAccountant 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)
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April 11, 2023@Debashis Saha, IIM Calcutta
60Network Management OVERVIEW
Security Measures
• Physical Layer: covert channel,
spread-spectrum
• Data Link Layer: link encryption
• Network Layer: packet-filter
• Application Layer:firewall,
cryptography
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April 11, 2023@Debashis Saha, IIM Calcutta
61Network Management OVERVIEW
Secret Key System
Alice Bob
DES Key DES Key
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April 11, 2023@Debashis Saha, IIM Calcutta
62Network Management OVERVIEW
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
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April 11, 2023@Debashis Saha, IIM Calcutta
63Network Management OVERVIEW
Looking Forward
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April 11, 2023@Debashis Saha, IIM Calcutta
64Network Management OVERVIEW
The Power of “O”
YOUR BUSINESS
High data rate ~ Tbps
High reliability of fibre ~ 30 years
Low error rate < 10^(-6)
Un-repeatered over longer distances
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65Network Management OVERVIEW
The Power of “M”
YOUR BUSINESS
Handy devices Consumer oriented
Freedom for movement
Anywhere, anytime
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66Network Management OVERVIEW
Future = Optical + Mobile
• Wireless mobile communication has already attracted global attraction
• DWDM optical technology is maturing at a very high speed
• Future global trends show-
Wide-spread adoption of wireless mobile
access to optical backbones