LAYERS OF TCP/IP

1. Topic : Basics of WAN & WAN Protocols
Sub-Topic : Describe Different Layers of TCP/IP
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2. Recap
In the previous classes, you have learnt about
• Packet transfer mechanism in Routers using IP address
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3. Objectives
On completion of this period, you will be able to know
about
• Functions of different layers of TCP/IP
• Various protocols used in different layers
• Importance of TCP/IP architecture
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4. Recap
What is the network architecture that we have already
studied ?
ISO – OSI Model
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5. How many layers it has and name them ?
Seven -
Application
• Presentation
• Session
• Transport
• Network
• Data link
• Physical
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6. OSI Model
Application
Presentation
Session
Transport
Network
Data link
Physical
Fig .1
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7. Need for TCP/IP
• OSI model has seven layers in it
• Two of the layers namely presentation and session
layers were rarely used
• OSI architecture is rigidly structured
• As the technologies developed there was a need for a
new architecture
• Presentation and session layers are eliminated
• TCP/IP architecture has evolved to overcome the
shortcomings of OSI model
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8. TCP/IP Model
Application
Not present
in the model
Transport
Internet
Host-to-network
Fig .2
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9. Layer Level Comparisons
OSI TCP / IP
Application Application
Transport Transport
Network Internet
Data link
Host-to-Network
Physical
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10. Differences in Architectural Models
• OSI Network architecture model does not permit
communication between different heterogeneous
networks
• It does not support the latest networks developed
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11. Differences in Architectural Models
(Contd…)
• TCP/IP network architecture allows us to communicate
between any heterogeneous networks
• It is flexible and ready to change its architectural
structure to support the newly introduced networks
• For Ex: The wireless communication networks also can
be interconnected to the existing wired networks
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12. Functions of the TCP/IP Layers
Host-to-Network Layer
• It is the lowest layer in this model
• It is equivalent to the Physical layer of OSI model
• The TCP/IP reference model does not really say
much about what happens in this layer
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13. Host-to-Network Layer (Contd…)
• It points out that the host has to connect to the
network using some protocol so it can send IP
packets over it
• This protocol is not clearly defined and varies from
host to host and network to network
• It is concerned with the physical characteristics of the
medium, connectors, voltage levels etc
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14. Internet Layer
• Internet layer is the lynchpin that holds the whole
architecture together
• Its job is to permit hosts to inject packets into any
network and have them travel independently to the
destination
• The destination can be in a local network or different
network
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15. Internet Layer
•They may even arrive in a different order than they were
sent, in which case it is the job of higher layers to rearrange
them
•The internet layer defines an official packet format and
protocol called IP (Internet Protocol)
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16. Internet Layer ( contd…)
• Packet routing is clearly the major issue here, as is avoiding
congestion
• This layer also performs congestion control i.e. it can divert
the data traffic to other routes to ease the congestion
• TCP/IP internet layer is very similar in functionality to the OSI
network layer
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17. Transport Layer
• The layer above the internet layer in the TCP/IP model
• It is designed to allow peer entities on the source and
destination hosts to carry on a conversation
• Two end-to-end protocols have been defined here
a) Transmission control protocol
b) User data gram protocol
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18. Transport Layer (Contd…)
•The first one, TCP (Transmission Control Protocol) is a
reliable connection-oriented protocol.
•It fragments the incoming byte stream into discrete
messages and passes each one onto the internet layer.
•TCP allows a byte stream originating on one machine to
be delivered without error on to any other machine in the
internet.
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19. Transport Layer (Contd…)
• At the destination, the receiving TCP process
reassembles the received messages into the output
stream
• TCP also handles flow control
• It makes sure that a fast sender cannot swamp a slow
receiver with more messages than it can handle
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20. Transport Layer (Contd…)
UDP Protocol
• The second protocol in this layer is UDP (User Datagram
Protocol)
• UDP an unreliable, connectionless protocol for
applications that do not want TCP’s sequencing or flow
control
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21. UDP Protocol contd…
•It is widely used for one-short, client-server type request-
reply queries
•It is used in applications in which prompt delivery is more
important than accurate delivery, such as transmitting
speech or video
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22. Protocols and Networks in the
TCP/IP Model Initially Layer
(OSI names)
TELNET FTP SMTP DNS Application
Protocols TCP Transport
UDP
IP Network
SATNET PACKET LAN Physical +
Networks ARPANET
RADIO Data link
Fig .3
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23. Application Layer
• TCP/IP model does not have session or presentation
layers
• On top of the transport layer is the application layer
• It contains all the higher-level protocols
• The early ones included virtual terminal (TELNET), file
transfer (FTP), and electronic mail (SMTP)
• TELNET, the virtual terminal protocol allows a user on
one machine to log into a distant machine and work
there
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24. Application Layer (Contd….)
• The file transfer protocol provides a way to move data in
the form of files efficiently from one machine to another
• SMTP (Simple Mail Transfer Protocol) also called as
Electronic mail
• It was originally just a kind of file transfer, later a
specialized protocol was developed for it
• Domain Name Service (DNS) for mapping host names
onto their network addresses
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25. Application Layer (Contd….)
•Hyper Text Transfer Protocol (HTTP), the protocol used
for fetching pages on the World Wide Web
•DNS is used to translate the email ID into IP address.
Users can identify themselves through email ID
•Network News Transfer Protocol (NNTP) the protocol
used for moving news articles, which will be used by the
news paper companies
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26. Summary
In this class, you have learnt about
• Functions of various layers in TCP/IP
• The various protocols used in TCP/IP along with their
importance
• The TCP/IP architecture and its functions
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27. Quiz
1) This layer deals with the physical transmission medium
a) Host-to-Network
b) Internet layer
c) Transport layer
d) Application layer
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28. Quiz
2) TCP protocol is related to which layer
a) Host-to-Network
b) Internet layer
c) Transport layer
d) Application layer
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29. Quiz
3) UDP protocol is related to which layer
a) Host-to-Network
b) Internet layer
c) Transport layer
d) Application layer
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30. Quiz
4) IP protocol is related to which layer
a) Host-to-Network
b) Internet layer
c) Transport layer
d) Application layer
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31. Quiz
5) WWW can be accessed using this protocol
a) IP
b) UDP
c) HTTP
d) NNTP
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32. Quiz
6) News publishing companies use this protocol
a) IP
b) UDP
c) HTTP
d) NNTP
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33. Quiz
7) E-mail is supported by this protocol
a) IP
b) SMTP
c) HTTP
d) NNTP
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34. Quiz
8) Traffic congestion is the function of this layer
a) Host-to-Network
b) Internet layer
c) Transport layer
d) Application layer
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35. Frequently Asked Questions
Short Questions
1. Name the various layers of TCP/IP architecture ?
2. What are the functions performed by Host-to-Network
layer?
3. What are the functions performed by Internet layer ?
4. What are the functions performed by Transport layer ?
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36. Frequently Asked Questions
5. What are the functions performed by Application layer ?
6. What are the various protocols supported by TCP/IP
architecture ?
7. Briefly describe about TCP and UDP ?
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37. Essay Questions
1. Discuss in detail about TCP/IP architecture and explain
the functions performed by different layers ?
2. Discuss about all the types of protocols supported by
TCP/IP network architecture model ?
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