449838944-Lec-02-Network-Model-1-ppt.ppt

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1. Lec 2
Networking Model
1

2. C O N T E N T S
2.1 Introduction
2.2 OSI Models
2.2.2 Physical
2.2.3 Data link
2.2.4 Network
2.2.5 Transport
2.2.6 Session
2.2.7 Presentation
2.2.8 Application
2.2.9 Summary of duties
2.3 Internet
Models
2.3.1An exchange using the
TCP/IP model
2.3.2 Summary of duties
2.3.3 Comparison
2

3. Learning Outcomes
At the end of this lecture, you should be
able to
Elaborate the OSI layer
Elaborate the TCP/IP layer

4. 2.1 Introduction
4
Analogy :
Sending a
letter

5. 5
7. writing a
letter
6. translator
5. secretary
4. postmaster
3. addressing
2. check
1. transport1. transport
2. check
3. addressing
1. transport
2. check
3. addressing
7. read a letter
6. translator
5. secretary
4. postmaster
3. addressing
2. check
1. transport
KL
post office
Bejing
post office
Johor
post office
Shanghai
post office
van
car
a/plane
postmaster
English?
Cryptographic
language agreed on
ACK

6. 2.2 OSI Model
Established in 1947
The International Standards
Organization (ISO) is a multinational
body dedicated to worldwide
agreement on international
standards.
An ISO standard that covers all
aspects of network communications is
the Open Systems Interconnection
(OSI) model.
It was first introduced in the late
1970s.
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Session
Transport
Network
Data link
Physical
Presentation
Application

7. PDU & Encapsulation
Sender (Computer 1) Receiver (Computer 2)
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8. The interaction between
layers in the OSI model
8

9. 2.2.1 Function
9
DataH7
DataH6
DataH5
DataH4
DataH3
DataH2T2
www, FTP chat
mpeg, jpeg, doc
01101101101101
TCP, UDP
IP,HDLC, IPX
ATM, PPP, NIC, Ring
token, Bus
Cable, Hub
Open a telnet, do something in
between, close
Session
Transport
Network
Data link
Physical
Presentation
Application
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Session
Transport
Network
Data link
Physical
Presentation
Application

10. 2.2.2 Physical layer
The physical layer is responsible for
transmitting individual bits from one
node to the next.
Duties
Physical characteristic of interface &
media
Representation of bits
Data rate
Synchronization of bits
10
Transmission of bits on the
physical hardware

11. 2.2.3 Data link layer
The data link layer is responsible for
transmitting frames from one node to
the next.
Duties
Framing
Physical addressing
Flow control
Error control
Access control
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Framing of units of
information and error checking

12. 2.2.3 Data link layer:
Node-to-node delivery
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13. 2.2.3 Data link layer:
Node-to-node delivery
EXAMPLE: A node with physical address 10 sends a frame to a
node with physical address 87. The two nodes are connected
by a link. At the data link level this frame contains physical
addresses in the header. These are the only addresses needed.
The rest of the header contains other information needed at
this level. The trailer usually contains extra bits needed for
error detection
13

14. 2.2.4 Network layer
The network layer is responsible for
the delivery of packets from the
original source to the final
destination
Duties
Logical addressing
Routing
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Packet delivery, including
routing

15. 2.2.4 Network layer:
Source-to-destination delivery
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16. 2.2.4 Network layer:
Source-to-destination delivery
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EXAMPLE:Letsaywewantto
senddatafromanodewithnetwork
addressAandphysicaladdress10,
locatedononeLAN,toanodewith
anetworkaddressPandphysical
address95,locatedonanotherLAN.
Becausethetwodevicesarelocated
ondifferentnetworks,wecannotuse
physicaladdressesonly;thephysical
addressesonlyhavelocal
jurisdiction.Whatweneedhereare
universaladdressesthatcanpass
throughtheLANboundaries.The
network(logical)addresseshavethis
characteristic

17. Provision of reliable and
unreliable end-to-end delivery
2.2.5 Transport layer
The transport layer is responsible for
delivery of a message from one
process to another.
Duties
Port addressing
Segmentation & reassembly
Connection control
Flow control
Error control
17

18. 2.2.6 Session layer
The session layer is responsible for
maintains, establishes and synchronizes the
interaction between communicating
systems.
Dialog control
allows two systems to enter into a dialog
(communication between two process.)
Synchronization
allow a process to add checkpoints into a
stream of data
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19. 2.2.7 Presentation layer
The presentation layer is responsible
for syntax and semantics of the
information exchanged between two
systems
Translation
the running programs must be
changed to bit streams before being
transmitted.
Encryption / Decryption
to carry sensitive information, a
system must be able to ensure
privacy.
Compression
reduces the number of bits
contained in the information.
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20. 2.2.8 Application layer
The application layer is responsible for providing
services to the user.
Duties
Mail services
File transfer and access
Remote log in
Accessing WWW
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Provide network
application such as file
transfer

21. 2.2.9 Summary of duties
Application–to allow access to network resource
Presentation –to translate, encrypt and compress data
Session –to establish, manage and terminate session
Transport–to provide reliable process-to-process message delivery and
error recovery
Network–to move packets from source to destination, to provide
internetworking
Data Link –to organize bit into frames; to provide hop-to-hop delivery
Physical–to transmit bits over a medium; to provide mechanical and
electrical specifications
21

22. 2.3 TCP/IP Model
The layers in the TCP/IP Model do not exactly match
those in the OSI model.
The original TCP/IP model was defined as having four
layers: host-to-network, internet, transport, and
application.
However, when TCP/IP is compared to OSI, we can say
that the TCP/IP Model is made of five layers: physical,
data link, network, transport, andapplication.
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23. 2.3 TCP/IP Model (cont.)
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Application
Transport
Internet
Network Access
Application
Transport
Network
Data link
Physical

24. 2.3.1 An exchange using the
TCP/IP model
24

25. 2.3.2 Summary of duties
Application–to allow access to network resource
Transport–to provide reliable process-to-process message delivery and
error recovery
Network–to move packets from source to destination, to provide
internetworking
Data Link –to organize bit into frames; to provide hop-to-hop delivery
Physical–to transmit bits over a medium; to provide mechanical and
electrical specifications
25

26. 2.3.3 Comparison
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Application
Transport
Network
Data link
Physical
Session
Transport
Network
Data link
Physical
Presentation
Application

27. 2.3.3 Comparison
27

28. Any
Questions?