The document discusses the OSI reference model, which was introduced in the late 1970s by the International Organization for Standardization (ISO) to establish a standard for network communication. The OSI model defines seven layers of network functionality, including the physical, data link, network, transport, session, presentation, and application layers. Each layer has a specific role, with lower layers focusing on physical connectivity and higher layers dealing with process-to-process communication between applications. The document also covers addressing schemes like MAC addresses, IP addresses, and port addresses used in TCP/IP networks.

1. Chapter 6
OSI Reference Model
Data Communications
1By Chhay Buntha

2. We use the concept of layers in our daily life. As an
example, let us consider two friends who communicate
through postal mail. The process of sending a letter to a
friend would be complex if there were no services available
from the post office.
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.
Layered Tasks of the OSI Model
Chapter6
2By Chhay Buntha

3. Tasks involved in sending a letter.
Chapter6
3By Chhay Buntha

4. Chapter6
4By Chhay Buntha
ISO is the organization.
OSI is the model.
Note

5. Seven Layers of the OSI Model
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5By Chhay Buntha

6. The interaction between layers
Chapter6
6By Chhay Buntha

7. An exchange using the OSI model
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7By Chhay Buntha

8. Layer1: Physical Layer
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8By Chhay Buntha
-Physical Characteristics of interfaces and medium
-Representation of bits: Stream of bits 0s and 1s
-Data Rate
-Synchronization of bits
-Line configuration: Connection
-Physical topology
-Transmission mode: Simplex,Half/Full duplex

9. Layer2: Data Link Layer
Chapter6
9By Chhay Buntha
-Framing: convert from up layer to frame
-Physical addressing: MAC (Media Access Control)
-Flow/Error/Access control: Make error free to upper

10. Layer3: Network Layer
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10By Chhay Buntha
Responsible for the source to destination delivery of a packet.
-Routing
-Logical addressing: IP Address

11. Layer4: Transport Layer
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11By Chhay Buntha
Responsible for process-to-process delivery of the entire
message:
-Flow/Error control
-Connection control: Connectionless and connection
oriented

12. Layer4: Transport Layer
Chapter6
12By Chhay Buntha

13. Layer5: Session Layer
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13By Chhay Buntha
Responsible for established the connection between
communication systems

14. Layer6: Presentation Layer
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14By Chhay Buntha
-Translate
-Encryption/Decryption

15. Layer7: Application Layer
Chapter6
15By Chhay Buntha

16. Summary of Layers
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16By Chhay Buntha

17. Addressing
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17By Chhay Buntha
Four levels of addresses are used in an internet employing
the TCP/IP protocols: physical, logical, port, and specific.

18. Physical Address: MAC Address
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18By Chhay Buntha
Most local-area networks use a 48-bit (6-byte) physical
address written as 12 hexadecimal digits; every byte (2
hexadecimal digits) is separated by a colon, as shown
below:
07:01:02:01:2C:4B
A 6-byte (12 hexadecimal digits) physical address.

19. Logical Address: IP Address
Chapter6
19By Chhay Buntha
An IPv4/IPv6 addresses is a 32/128-bit address that
uniquely and universally defines the connection of a device
(for example, a computer or a router) to the Internet. Figure
below is the sample of IPv4 address.

20. Port Address
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20By Chhay Buntha
A port address is a 16-bit address represented by one
decimal number as shown.
753
A 16-bit port address represented
as one single number.

21. Special Address:
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21By Chhay Buntha
What is a special address?
- www.google.com
- www.ppiu.edu.kh
- www.dap-news.com
- 127.0.0.0