Intro to Data Communication

1. Lecture 3
Introduction to Data
Communication
Tameru H.
AASTU, Department of Software Engineering 1

2. Network layer
2
End-to-End packet delivery
From the original source to a destination
Needed when 2 devices are attached to different
networks
Main duties:
1. Logical addressing
2. Routing
3. Switching
4. Congestion control and QoS

3. Source to destination delivery
3

4. Example
4
Data Link layer
addresses
Network layer
addresses

5. Transport Layer
5
Process-to-Process delivery of the entire
message
From the original source to a destination
Needed when several processes (running
programs) active at the same time
Main tasks:
•Port addressing
•Segmentation and reassembly
•Congestion control
•Flow control
•Error control

6. Cont'd...
6

7. Example
7

8. Session Layer
8
The session layer is responsible for dialog
control and synchronization.

9. Presentation Layer
9
The presentation layer is responsible for translation,
compression, and encryption.

10. Application Layer
10
• Enables user to access the network
• Provides services to a user
 E-mail
 Remote file access and transfer (Telnet,
FTP)
 Access to WWW

11. Four Level of Addresses
11

12. Cont'd...
12

13. 13
Question ???